I meant for 2018 and beyond naturally, the 2017 lineup is already well known. In the style of Quantum Break, Crackdown and such where it's a third party studio working on either a Microsoft IP or an entirely new one. If there aren't, then we can basically guess at the entire Microsoft output through to Holiday 2019, which will be "Another Halo, Two Forzas, Another Gears, and 2-4 small games".
343 and The Coalition seem to be 1.5 game studios - able to do a bit of remastering or helping out another studio on the side while they work on their big game. But unless there's been a hiring spree (which I don't think we've heard about), I can't see them having 2 large games in full development simultaneously. Turn 10 and Playground are always on the Forza train. Rare will by busy with the launch and postgame support for Sea of Thieves, although they probably can start developing something on the side while that's going on. Mojang is Mojang.
The only place I can really see surprises coming from then are third party contracts. Halo Wars 2 was a collaboration with Creative Assembly/Sega and 343 industries. Recore is a collaboration with Armature/Comcept. Crackdown 3 is a collaboration with like 12563463 different studios for various things apparently.
Looking at the current slate of known Microsoft games coming out, there are only two explanations - either they really are winding down first party support to the bare, profitable minimum, or there was a reorganization that led to several cancellations and a gap in their lineup before new projects were ready for announcement and shipping. I hope it's the latter, but have there been any leaks hinting towards this? Do we have any rumblings that there's stuff in the works we'll be excited about?