New xbox this year is a possibility, but I don't see it happening until at least next year. They might surprise me though. What I do know is they won't release a Halo HD trilogy. Halo 1 has already been done (and thus would piss off too many people if they tried to release it again so soon) and Halo 3 is already in HD and looks gorgeous as it is. Halo 2 is the only title that stands to be given the HD treatment. With Anniversary the graphic overhaul was amazing and I definitely see 343 wanting to repeat the process for Halo 2, but honestly I would be okay with a basic graphical overhaul. Unlike Halo 1, which had blatantly dated graphics, Halo 2 did not. It was one of the best looking games on the original Xbox and were it not for the lack of HD, would probably still look better than a handful of the games coming out for the 360 now.
At this point, they absolutely have to release a Halo 2 HD release. I took time earlier today to readjust my CD Binder and built in a spot for Forward Unto Dawn that came in the mail today and set a spot for Halo 5 and 6. I also went ahead and made room for Halo 2 Anniversary, so they bloody well better do it!