As a gamer, I've always had faith in Carmack when it comes to developing solid software....because that's where his strength lies. Despite that, my skepticism in id Software grew over the years because he was only one member of a team that seemed incapable of doing anything interesting with his work.
Same here. I'm confident that John Carmack wants to build a kick-ass, immersive experience.
I have no confidence that the higher powers at Facebook will let him realize that goal without weighing him down with a dozen other corporate needs, to justify the cost of acquisition.
No, see, there's you're problem. History has proven that Will Wright always underdelivers on anything he hypes up. The guy that designs The Sims is not going to design a realistic evolution simulator.