I think the next big genre will be the MMOFPS. In fact, I think most of the players playing MMORPGs want more FPS action and less RP (though they do want some), and will find the answer to their MMO dreams in an First Person Shooter oriented game.
Borderlands is an excellent example of what I'm talking about, and BL 2 (BLT as some of us like to say), coming out in September, will be even more so. BL isn't an MMO, its multiplayer is limited to 4 players, but the developers of the game are now using the term "Roleplaying Shooter" - RPS - to describe it and I think it fits.
So, I think Romero is on the right track, assuming, as some of you have said, he can put a serious and talented team together to do it.
😉