Halo 1 Anniversary was developed by Saber Interactive. It seems like they are currently working on a yet-to-be-announced Xbox One exclusive. Could it be the recently rumored Halo 2 Anniversary?
Vyacheslav Solovov is the Head of Concept Art Department at Saber Interactive and he is currently working on an Xbox One game, which hasn’t been announced yet. We can see the game listed in his portfolio here.
It was earlier rumored this week that Halo 2 Anniversary is real and is heading to the Xbox One this year. The game was supposed to be the Halo game to release on the Xbox One this year and would replace Halo 5, which got delayed next year, as per the rumors.
If Saber Interactive is indeed working on such a game, it is not far fetched to assume that they will also work on porting Halo 2 to the Xbox One, just like they did with Halo 1.