Paraphrasing Dan Spitzley:
So yeah, I would like to see ScottE working on a new Fallout game, or read some dialog by Huggies, his lines in van Buren are awesome, or poke Sawyer and Fergus a bit more ("That's not canon! You need more sleep!") , even if it was a handheld Fallout Advance: Tactics game, or a spiritual successor Bioshock style.
But the reality is if they tried to make a RPG then it had to be a Next-Gen simplified game for consoles, since it's all everyone can do these days, and that is already covered. And Bethsoft will stick with the Fallout games for themselves anyway, this is just academic.