I hope people realize that the transition to 28nm means they can fab the same GPU on less silicon. A die shrink doesn't mean they're going to fab a GPU with the same surface area as a 40nm GPU but with 85% more ALU's, because that wouldn't make sense at all.

Odds are they're going to use the die shrink to crank out a higher number of GPU's to meet (hopefully high) demand. With the move away from VLIW, it's anyone's guess as to how the on-die real estate will get divided up.