I think that it won't really matter whether Bethesda or Obsidian makes the game, they're both smart enough to take a look at what New Vegas did and it's reception and incorporate what worked and what didn't into the next game, so it'll probably be good either way.
EDIT: Also, while I'm aware of it, I don't get this complaining about bugs in Bethesda and Obsidian games, the most I've ever seen is the occasional rock with part of the texture missing, that's it. Maybe it's because my computer is able to run the Fallout and Elder Scrolls games with plenty of computing power to spare, or I've been VERY lucky, I don't know.
As for the location, I'm hoping they aren't going for Boston. Why? It's just because it's not that well known of a location. I've never been anywhere near D.C. but I can take a look at the Lincoln Memorial or the Washington Monument in a game and know instantly what I'm looking at. I also know Vegas well enough despite never being within 500 miles of it to know it's largely about gambling and such, not to mention New Vegas' general western theme is something everybody knows. In short, they're locations just about anybody can identify with no matter where in the world they live, which is important because Fallout is intended to reach a worldwide audience, and that's easier to do if the game takes place in a location most have at least a passing knowledge of.
Boston? Not so much. I don't even have a clue what the place looks like, what kind of monuments it has if any, and pretty much the only event I can think of in history that's notable in Boston is the Boston Day Massacre, which is a pretty minor footnote when it comes to American history.
A place like Chicago or New York would probably work better, Chicago since the 50's mobster era would fit perfectly with Fallout's overall theme, while New York is a place with lots of identifiable landmarks, would be a place that probably would have been hit pretty heavily by the bombs, and both are pretty well known major U.S. cities in their own right.
This is under the assumption they'd stick to America of course, a place like London or Paris or somewhere like that would be good for a setting out of the good ol USofA, since they have yet to explain what the hell happened to the rest of the world in the 200 years since the apocalypse.
