Would id Tech 5 really be suitable for a TES game anyway? Id engines are usually more geared towards smaller, discrete levels, rather than gigantic sprawling megaworlds. I mean, Gamebryo is buggy as hell, but if you consider all the stuff it has to deal with at once, not just streaming in graphics as you're walking around but all the pathing of NPCs and keeping track of all the little changes you've made to the world, its still kind of impressive. When its not crashing every ten minutes anyway.
I hope they make the motionless staring conversations a bit more natural, though. They still kind of freak me out.
PS. Also modding is really really easy in Gamebryo, so that's nice too, since there's almost always some stupid crap that needs fixing in Bethesda games.