Well, I wouldn't say Fallout was made for a mainstream market either. By definition, a Fallout styled game is not usually directed at mainstream game players. The question is whether they can make a Fallout style game profitable today, given the rising costs of game development.
What game mechanics made Fallout a successful game and how would you implement and change them to adapt them to today's gamer expectations? Would a more open ended NWN2 do the trick?