The death of Adolf Hitler on August 20, 1939 - the consequences...

[The Banker]

1 War with Poland was part Nazi philosophy and part Hitler's choicd. Stopping the war isn't impossible, but there's not much time - an anti-war replacement would have little time to act, and would therefore need to be strong enough to defeat pro-war factions within a week and a half. It's not impossible, just very difficult to see how it could be done.
2 War with the Soviet Union is inevitable from anti-communist side of the nazis and because adjoining spheres of influence will generate friction. Lebensraum requires defeat of the soviet union, coexistence virtually guarantees conflicts.
3 and 4 It's not impossible for them to come to an accommodation, but both parties mistrusted each other and had inherent political differences. The Molotov Ribbentrop Pact would result in Soviet Estonia, Latvia and (most of) Lithuania excep thd Memel pocket. Then thrre's Bassarabia and other parts of Romania. Conflict is, if not inevitable, very likely.
Mussolini would most likely stick with Africa and the Balkans - he only moved of France (and tbus UK) when he thought France was beaten. Here - who knows? My thoughts are that Barbarossa is unavoixable due to Lebensraum, which means France has to be neutralised first - and soon enough to prevdnt the soviet rearmament from advancing too much.

No or limited western Europen conflict allows stronger opposition to Japanese expansion. They may suffer badly for this, wjether through troop numbers, equipment availability (notably tanks, AT weapons and aircraft) and commanders - Singapore, for example was on a knife edge and could have been saved (at least temporarily) with only a few minor changes, and Percival backed by or supporting Auchinleck or Montgomery might have seen a very different outcome.
The big question is the USA, but Japan was aware of the danger the US and Phillipines posed to supply lines, and could well do more or less as OTL.

Very good answer
You seem to be a railroader. I am NOT saying this in a negative way. Some events in history are inevitable and I liked your answer. I am a railroader myself

 

[NoMommsen]

By late Agust, Germany was pretty much committed to war with Poland, mostly because they never really wanted a deal. ...

... well ... I tend to disagree.
Germany as such - if there is anything as a nation as an acting entity or adressable 'person' at all - could best be seen represented by its populace and as @Petr K. has already hinted at:

this 'entity' was far from wanting any kind of war at all as the "Meldungen aus dem Reich" clearly showed.​

That aside what the followers of Hitler and power groups within the german state wanted regarding Poland ...
was not a war (though many accepted such an outcame rather easily given some 'safe' military situation as a well possible means) but a revision of the german-polish border - preferrable the 1914 border if possible with some additional ... 'safty margin'.
If such a first change - maybe seen by some as a 'first step' towards the 'final goal' - could be achieved without a war these groups would have been very happy with.
... even ... or esp. (?) the military. But aside the biggest faction still stunned and silenced by the achievements of Hitler so far (München, taking of Memel, creating the protectorate and the 'vassal' state of Slovakia) there still was even in summer/August a military opposition 'advertising' some coup though even smaller than in 1938 and with less (positive) responses.

If Goering tried to call it off, he would risk recriminations for failing to respect Hitler's legacy, or for lack of moral fibre, and might well annoy the army. So even if he wanted to avoid war (and I'm doubtful he did), there's a lot of pressure to continue, and he may not have enough time to stop it if the transfer of power doesn't go smoothly, and if he did, there is a possibility that Goering has a rapid - and likely fatal - fall from power.
...

IF Göring strikes any kind of deal with whatever 'win' he would very likely be greeted by the german populace as well as the vast majority of civil service members and other rather 'conservative' parts of the system militaries as well as the military many very well aware of its shortcommings in terms of trained men and material (some individuals lamenting of having missed their 'moment of glory' for the moment) and celebrated as german Chamberlain returning from München 1938.
All Güring could win with gains by diplomacy avaoiding war would let him look only more as the 'true' heir of Hitler matching him in diplomatic genious.

...
Then you have the problem that Lebensraum is fundamental to the nazi party, so unless Goering can purge that substantial faction, he's under pressure to head east, ...

IMHO Göring would certainly conduct some kind of 'purge' throughout the system and the party esp. though probably not in the kind of a "night of the long knives". For that he had other to the still essential 'traditional' power groups of military civil service and industry and economy more 'acceptable' means.
... aka the Gestapo and the though only flimsy 'cover' of legal 'police work'.
The kinds of Esser, Streicher, maybe even Himmler and Goebbls (the one with the least power base of its own if any at all) would be removed from political influence, maybe Rosenberg like put on powerless but 'nice' sounding posts for some time.
Some alike Hess - if not playing along - might 'suddely' accused of something illegal ... as i.e. homosexuality (there were IOTL enough rumors about) and vanish within the 'legal system' of the time.
'Learned' opportunists - like Bormann - would rather quickly 'accepts' the new Führer as being named by the eternal Führer as his heir.
The removal of these 'hot-heads' from public function would only gain Göring even more 'acceptance' from within said power-groups.

'Lebensraum' ... was esp. at that point of time a concept seen different even within the party and the 'Generalplan-Ost' varity was only in the minds of few even wihtin the party and far from generally communicated though without a doubt in 'Mein Kampf' and other statements enough 'hints' were given.
How seriously these then still cloudy and their earnty questioned by many concepts were to be taken ... can only we 'hindsighteers' judge.
Many rendered the 'Lebensraum' concept still more in kinda 'Mitteleuropa' concepts

- maybe 'only' aquiring the eastwern nations as a commercial exploitation zone​

- maybe somewhat enlarged than 1914 (when its extend was also rather undefined)​

- maybe with some additional 'settlers-policies'​

- maybe coupled with some partial expulsion-policies​

- etc. etc.​

but mostly ALSO rendered a process of decades and not within one. There was quite a range of differing conceptions of Lebensraum.

... which in turn requires France to be broken to avoid being attacked during Barbarossa.

And not seldom Göring mentioned his 'preference' of beating militarily the western powers as revanche instead of some anti-russian-anti-communist crusade which he envisaged if then in complicity with the west.
(... however ambivalent this sounds but ... the whole Nazischaft was as ambivalent as - simply - is human nature)

 

[NoMommsen]

Hello. Can anyone tell me the outcome of this discussion.

1)Was war with Poland inevitable?
2)Assuming it doesn't happen, was war with the USSR inevitable?
...

... Some events in history are inevitable and I liked your answer. ...

Well ... IMHO history as being determined by actions of humans which are seldomly predictable (or rather far from for us today) esp. not if there's a combination of these (human version of a "Three-Body-Problem ... not the of netfix stuff ) there are no 'inevitable' events at all.

1 War with Poland was part Nazi philosophy and part Hitler's choicd. Stopping the war isn't impossible, but there's not much time - an anti-war replacement would have little time to act, and would therefore need to be strong enough to defeat pro-war factions within a week and a half. It's not impossible, just very difficult to see how it could be done.
2 War with the Soviet Union is inevitable from anti-communist side of the nazis and because adjoining spheres of influence will generate friction. Lebensraum requires defeat of the soviet union, coexistence virtually guarantees conflicts.
...

At first:
to "crush" Poland in a war was never part of whatever might be called "philosophy"of the Nazis.
As said above reverting Versailles and esp. the german eastern border was raison d'etre for EVERY german goverment from the signing of the ToV onwards with only the assumed/proposed means changed from opportunity to opportunity and between personal taste(s). It was far from something especially 'Nazi'.

At second:
Same is valid for the anti-communism. There were ven 'thinkers' within the Nazi establishment as well as in the whole political german community right of the communists (including SPD) that sported the idea of a kinda 'second' revolution in russia overthrowing the actual communist regime (not necessarily by zarists) or the breakdown of the soviet system by itself.
The military option ... was one of several and not necessarily the most wanted.
About 'Lebensraum' and its 'war demanding weight' ... see above post. And therefore I won't attach any 'inevitablitity' to Barbarossa as well.


... more general ...

... Nazi philosophy ...

IMHO it is too much to attest the Nazis whatever kind of "philosophy" or "ideology" at all. It was a hotch-potch of many ideas even contradictory ones for everybodys taste to pick.
Hitler - who's wishes and assumed opinions were the only 'guidance' of what shall happen or been done - was far from the intellectual capacity to formulate something alike. There ARE no (intellectually consistent) writings of any kind of ideology like the works of Lenin or Stalin. Even what Mussolini had ever written was more consitent as an ideolgy than whatever came from Hitler especially.

Even Hitler utterings - may them occur within Mein Kampf or stated on whatever kind of public appearence or even not so public appearences - were also far from canonical though sometimes used as in internal fights between Hitlers 'lieutenants' (mafia-like thought ).
There were attempts to put down some kind of ... 'katechism' or 'sunna'.
Hitler himself was keen to kill these in their cradle. He didn't wanted to 'pinned down' even on his own statements and keep a tight control of every interpretation of these by approval or non-approval may it be direct or more often indirect.

'Generalplan Ost', 'Hungerplan' and their 'creators Konrad Meyer and Herbert Backe - not to say there weren't a plethora of other 'plan' and men developing and forwarding such plans - and their like were attempts of giving some of Hitlers utterance some form by technocrats as tasks given them through their superiors acting as intermediates to said wishes.
And for technocrats within Nazi-controlled Germany applied: the more radical your ideas the more attention you gain. ... and 'attention' was (and is) the currency for climbing the career ladder. Not given such tasks scuh plan might never have occured that we of today can 'rage' over them.

 

[CaptainCalvert]

Very good answer
You seem to be a railroader. I am NOT saying this in a negative way. Some events in history are inevitable and I liked your answer. I am a railroader myself

One interesting point about Hitler's death on 20th August is that it prevents him giving the speech on 22 August in which he basically gave permission to commit atrocities in Poland. He's also not around to give the Fuhrer directive in mid September which pretty much laid out the destruction of Poland and its people.

So there's a reasonale prospect that ITTL Poland in general has a slightly better time than OTL (which still leaves plenty of scope for it being terrible). The absence of a general instruction to behave terribly should also improve behaviour in any future soviet war, although again that still leaves much scope for atrocities and all round misery.