I really want you guys to think about something:
China didn't have a vault program
Nor did Europe/the British isles/The Middle East
In fact, Europe would have nothing left. The resource wars destroyed all semblance of actually being able to brave through a goddamned nuclear war, due to the fact that it left all of the countries in a state of being just barely 2nd world countries.
Anybody that survived the initial attack would've been killed off by the massive amounts of fallout, unless they were ghoulified.
Ergo: Those pushing for an Asian/European Fallout setting: Enjoy your game about rifling through rubble and occasionally fighting a ghoul.
My two cents:
Have it be in the core region again. That would be nice.
EDIT:
Who ever said the plot always revolved around the US in the game? Each game it's a different plot that has no or little effect on future plots. They could set it anywhere.
See: All of the other countries got forgeted.