I wouldn't really consider Halo Anniversary to be a new Halo game, but I get what you're saying. I'm always bouncing the thought of a Halo 2 Anniversary back and forth in my head and whether I'd really want it or not. The thought of having the multiplayer brought back to Xbox Live with a new current gen shine sounds quite appealing... but the campaign, I'm not sure. The again, that wouldn't work this year anyways, seeing as it wouldn't be Halo 2's 10 Year Anniversary.
At any rate, it would be cool to have every original entry playable in a version fitted for the same console generation.