I presume this game will be the biggest CONSUMER game ever at 10+GB. With a texture-plenty game like this that shouldn't use compression (I mean, there's 50% of closeups!) and falling RAM prices these days...
If they use procedural synthesis to generate textures it's hard to estimate a Q4 '06 or even Q1 '07 launch.

(BTW the size is exceeding Myst IV, which I thought was quite awsome despite it's FMV. And rendered in 3DS MAX.)

I doubt this game will be on X360. The highest they've reached to is Prey that is going gold (Quake 4 engine) and Gears of War (Unreal 3) that comes Q4 '06, and is heavily optimized by the codemasters at Epic.
I expect UE3.5K to be the common middleware for 2007/8 FPSes, which might still not shine compared to Crysis.

This post has been edited by X.E.D: Jul 2 2006, 11:09 AM