Source It sounds like a possibility to me, It would certainly help sell a new Xbox Console however if that’s the case it don’t look like we will see another Halo game for a few years... which is fine by me.
3 years between Halo 2 and Halo 3 so I think I'll be able to wait as well. People will keep playing the MP that's for sure, heck some might want to give the SP another go. Good thing about games like Halo is that they add new content to keep things interesting and I don't think it's possible to get bored of forge, well unless you run out of ideas that is.
Told you it wasn't going to be Bungie, or even a big studio I'm not sure this game is being treated as Halo 4, more just set in the Halo universe, a la Halo: Wars. While I agree that the next outing for Master Chief will be on the next 360, as far as I'm aware it'll be Bungie who make it, so it won't be in this game. More than likely, any spartans will provide a small character presence and will probably revolve around one other than John-117, i.e. Kelly or Kurt.