Microsoft's been on a binder of late, shuttering the likes of Halo Wars developer Ensemble Studios. From that, a new developer entity is being created. Just as its other studios seem at risk (namely Lionhead and Rare) for the same corporate reorganization, Microsoft is trying to quell those fears. Regarding both the Microsoft-owned Rare and Lionhead Studios, Microsoft Game Studios head Phil Spencer states:

The work that those studios are doing [is] incredibly important to MGS. For Rare, this will be their fifth game in the first three years of the Xbox 360 - that's crazy. Two launch games? What studio on the planet signs up for two launch games? That's just crazy. So the productivity and effort in those two studios is just great to see.

About the Microsoft-owned Lionhead, Spencer says there are "no plans" for a Bungie or Ensemble-type reorganization with Microsoft Game Studios, adding "the next Lionhead game is definitely an MGS game". What about the game after that? Phil Spencer - Part Two [Games Industry]