Leaving aside that Austria was a German semi-dependency by 1914 and they had no reason whatever to invade, there's the domestic side of it. Nobody on either side wanted to go deploying troops against "German brothers". You'll note that even when their interests were contradictory, which was often, Austria and Germany never really clashed majorly after 1871: they couldn't.
It must also be understand that public outrage about the actual assasination was much like public outrage in Britain about the violation of an obscure treaty made in 1837: a useful cover for pragmatic interests. the Germans would never go to war with anyone just because they offed an Archduke, so that's out.
It's not beyond possibility that some commie or anarchist could provide a nice anational equivelant to Gavrilo Princip (not given what happened to Stuergkh), but no communes are a-springing up. By 1914, the Austrian Social Democrats were one of the principal parties in the Reichsrat and the dominant socialist party in most of the monarchy, and the last thing they wanted was dead Hapsburgs: the end of Franz-Josef would raise deep questions about the monarchy itself, and the Socialists were committed to the integrity of the monarchy and opposed a variety of local "national-socialist" factions (which, given the often radical nationalist character of these groups, is probably the origin of "German national socialism") as well as the conventional nationalists.
Now, Hungary is a somewhat differant question (Hungary and Russia were the two places to have home-grown regimes after the war, of course), but without the war you certainly wouldn't see a "Budapest commune" in a position to get the German army involved.
Oh, and Germany would not "puppetise" Austria whether it wanted to or not: on both sides, the pan-Germanist lobby was strong. The Germans were the strongest national group in the Reichsrat (that is, parties that were actively "German", not the mostly-German all-Empire parties, the Catholic Socials and the Social Democrats), and pan-Germans became highly influential in Germany during WW1.