As disappointing as it was to see the survivor2299.com teaser site end up being a hoax, Bethesda making another Fallout game is a matter of when, not if. It's really the time frame we're more concerned about, and based on casting documents obtained by Kotaku, the wait for the next series installment might not be as far off as Bethesda's silence would indicate.
The documents are for a project codenamed "Institute" which detail the game's opening sequence -- narrated by the player character, not Ron Perlman, it would seem -- and the setting: Boston. This would go along with prior rumors about the Commonwealth, which stemmed from Bethesda employees reportedly researching the Massachusetts Institute of Technology for the game. Those rumblings sounded believable then and continue to now.
The Commonwealth, eh? Yeah, I'm into it.