Seriously, you people are debating the DirectX capabilities of the Xbox past, present and future? Who cares?
This is all you need to know. Whatever the capabilities of the next generation Xbox are, they will be inferior to what a PC is capable of and will continue to hold back the gaming industry from taking advantage of newer and/or better technology.
Back to topic, while it is always sad to see a software company have to part company with a franchise that they created, this is Halo we're talking about. It may have helped put the Xbox on the map but it is inferior to many other FPS out there both past and present. Unless you are a Halo myopian, who really cares?