Well, I didn't go through the whole discussion, but I read some parts of it. I think that the Fallout series should remain within the US. It would be cool to see what happened to China and many other places, but as pointed out already, the Enclave and BoS are solely American groups that would not belong in such places. The story would have to change so much that it wouldn't even be Fallout anymore. It'd be just another post-apocalyptic game, with the Fallout title attached to it for kicks. (And that's not what anybody wants.)
I also want to point out that Canada was annexed by the US. If the player were to visit Canada, they'd see a different enviroment and probably some different factions, but it's
still America. It might be interesting if there were some struggle between (what used to be) Canada and the United States though.
Maybe the Canadians want to seperate and reclaim their independence? I'm not sure if such a storyline would belong in Fallout, but it'd be kinda cool to watch that unfold.