I would sadly say no, I don't think it would work, and here's why:
The Fallout setting is patterned after the American 1950's image of the future. As such, as long as it's set in America, there is no problem. However, if you take it to another country, what happens? Would the setting there be the same as the American image? Or would they have followed their own country's image of the future?
More basically: Are you going to shoe-horn in the American version of the future on all of the other countries of the world, or are you going to throw out the fallout setting in favor of something that the country's people actually imagined and just keep the word "fallout" in the name to sell copies? There is no right answer here. Which ever way you go, you're either going to insult the people from that country or you're going to tamper with the formula that people know and love.
Besides, they still haven't even done Texas yet. Come on, Brahman Barons, Ten Gallon Hats, Oil Wells, Whore Houses, Cowboys and Indians, Mosquitoes the size of Geese, fighting off Super Mutants from inside the Alamo, raiding the Pantex facility (the last Nuclear Weapon construction company in the US), all the while the developer's choice of the ruins of Dallas, San Antonio, Ft. Worth, Houston, Lubbock, Austin, Waco, El Paso, and/or Corpus Cristi to explore. Hell, half of them could be done up into individual DLCs. I can definately see them doing a Texas Fallout game before they shoot themselves in the foot by moving to another country.