One thing that just came to mind if the Marvel Cinematic Universe, specifically Iron Man. Assuming the MCU isn't butterflied away by some really obscure shift in the timeline caused by no 9/11, and Iron Man gets made, how different would this movie be?
The reason I bring this up is because the first Iron Man begins with Tony Stark trapped in Afghanistan after going there with the US military to test his weapons, and his origin is him building his first suit to fight his way back to freedom. But no 9/11 means no War on Terror, which means the US never invades and indefinitely occupies Afghanistan, which means the plot of Iron Man wouldn't really be able to use Afghanistan in this way.
Is there any way to remove Afghanistan from the first Iron Man and keep the plot mostly the same?
Afghanistan in this movie was used as a modern substitute for Vietnam, which is where Tony was trapped in the comics. On that note, the Punisher TV show on Netflix also used Afghanistan to substitute Vietnam for Frank Castle's origin. So consider that too.
Afghanistan really was useful for writers using any kind of military angle for many years, because it was this forever war in a far-off hellhole with no end in sight. It really was kind of like a modern Vietnam in many ways, minus the conscription. You take out Afghanistan, a lot of stories would have to fundamentally change. If not, they just don't exist.