In an interview with IGN, Spencer discussed the possibilities of Microsoft released HD remakes of games like Halo: Combat Evolved and Halo 2:

We obviously have a lot of new things going on, so the thought of re-doing a bunch of things is probably difficult to just weave into the overall portfolio. If you can provide real value to the customer, there could be possibilities for that, but I don't spend a lot of time thinking about it.

Sony has already released HD versions of the God of War Collection and will follow-up with enhanced versions of the Sly Cooper series, Ico, and Shadow of the Colossus. Numerous third-party publishers, like Ubisoft and Warner Bros. are also eyeing HD remakes like Beyond Good & Evil and Mortal Kombat.

Microsoft Game Studios does have a few HD remakes available with the XBLA releases of Perfect Dark, Banjo-Kazooie, and Rez HD.

Where do you stand on HD remakes and re-releases? To me, it depends on the game. For example, I didn't get the God of War Collection because I had already played an finished both games on the PS2. In general, I'm content with simple re-releases if functionality, like multiplayer, is added or restored.

Would I want Halo 2 re-released for XBLA with online play restored? Yes, I would.