Fallout 3 did not suck, even after months you can pick up the game, start a new character and have fun. Hell, I haven't even gotten at the Bobbleheads yet, so I still have something to do when I pop in the game for a few hours. It never ceases to be fun and the downloadable content has been pretty good so far.
Personally, I doubt any of this is true however. Fallout 3 not only got every old school Fallout guy to buy it, but made itself a new audience too, many of which will NOT go for the Overhead perspective of the FO1, 2, Tactics, etc. Unless its another FPS with better story, and a meaningful SPECIAL (and speech skill), which would be GREAT!!, I don't see it ever being made.
I think its just a rumor.
Personally, I'd like to see a Fallout game NOT based in the USA. China would be interesting, we'd get to hear their side of the story. Or if it stays in the states Chicago would be sweet too, there is already a little story for that in FO3.