I could definitely see a sequel. If EA will spin off tons of Command & Conquers, why not Halo Wars? Anyhow, the Halo series is a sure-fire moneymaker for MS.
I do see MS making a Gears-type Halo, as well as a open sandbox kind of game - and even an RPG lite version, like Mass Effect (with power-ups).
So, IMHO, I can see MS doing:
1. Another Halo Wars RTS game
2. Halo RPG (like Mass Effect)
3. Halo 3rd person shooter







