In an interview with GameSpot during this year's E3 expo, Microsoft's Games Studios head Phil Spencer confirmed the company's intention to have all first-party developed games include Kinect functionality.
Speaking to GameSpot Spencer commented:
"It's not a mandate that everything we do in first-party has to support Kinect right now.
"But I will say, specifically with voice, that there are some things that just seem to make navigating and playing games so much easier, that I would guess the answer will be yes in the end, that you'll see all first-party games using some form of Kinect functionality.
"Whether it's voice in Forza or head-tracking in Forza, which you wouldn't say is somehow turning the Forza gameplay experience on it's head. Rather, it's just using the advantages of what Kinect brings to make the experience better. So I think there's some specific examples where Kinect makes everything better."
First-party developed games are those made by the same company that owns the console -- in this case Microsoft. Third-party developed games are those designed and made by studio's not belonging to the console's creator/owner.
The expo already saw Microsoft push to boost support for its Kinect peripheral. The company's press conference saw it announce a slew of new third-party developed games set to include Kinect support.
Spencer did not specify when this new policy would take effect, though he did indicate possible Kinect support for the newly announced Halo 4.