I probably wouldnt be too bothered if they make it using the Unreal Engine 4 and did it on the console after the 360. Though to keep interest in the series alive they could do a spin-off/expansion, along the lines of ODST. That might make slightly more sense to release along side Halo Reach and CoD 7 (because then the main game isnt getting slaughtered), but early 2011 would also work.