Well, most of what we expect to see from MS Studios have been announced already - Scalebound, Halo 5, Forza 6, Crackdown 3, Tomb Raider, Quantum Break, (and maybe Phantom Dust) or heavily teased / semi-confirmed - Gears of War, Battletoads. Is there really much else to leak besides blantly dropping the new trailer for those game (which would be a damn shame) ?
I am expecting Microsoft conference to be mostly about updates on those game, partly about confirmation for those teased projects, and very little about new announcements. After all we already know what most of their big studios are working on.