Oh dang! That man just ordered breakfast in the middle of my rap song!
If Bungie includes Project Natal into the control scheme for Reach...
a) It's not going to be required to play the game.
b) It's not going to replace the controller. Natal will work in conjunction with the controller we already have, and you can use motion control for small things, maybe opening doors, etc. There's no way Bungie will just scrap the controller for motion control, which, while it doesn't work well with an FPS on it's own, is a great supplement.