I have to say I can't help but notice an interesting thing on going when it comes to discussion of having a Fallout game in another locale:
When Fallout 3 came out, there were lots of people saying that all changes Bethesda was bringing to the table were irrelevant because "that wasn't what Fallout was all about." So apparently it's okay to change the way the game is played, how the rules work, etc - but the one line you absolutely cannot cross is that Fallout
must take place in America. Because the single most defining factor for the franchise was it's take on 1950's
American patriotism and optimism contrasted with a post-apocalyptic world. Apparently the single most defining factor for the franchise is an element that didn't fully come into it's own until the 3rd game in the series...
Let's not forget that in Fallout 1 and 2 that "50's Americana feel" consisted of a song that played during the intro sequence, vacuum tubes, (arguably) Vault Boy, and a velvet Elvis painting. It was Fallout 3 that really took that concept and ran with it. (And overall I think that was a good move - they did an incredible job with the art direction in this game, and because of that it somehow feels even more "Fallout" than the original games did.)
In the time frame that the game actually takes place in, all that's in the past. That "retro" vibe is relevant in that you're picking through the rubble of the "World of Tomorrow." But the actual denizens of the Wasteland - and the world that you're exploring - is "retro 50's" in the same way that the Byzantines were "Roman."
Back to the topic at hand - America wasn't the only country in the world for which the 1950s was a defining era. We'd just had a World War, after all - no matter where the game would take place, that's going to be a fairly iconic time; and that specific culture's view of what the future was going to bring would all have their own unique flavorings to bring to the table. In that vein, I think it could be quite interesting to have some spin-off games that take the Fallout experience to different countries. I'd say any country would be valid fodder for exploring what their concept of a Utopian future as envisaged by the visionaries of their day would look like blown to smithereens.