As a regular Obsidian backer/buyer (got PoE 1&2, Tyranny and all expansions) I'm very worried by that news.
Worried on the future content of the game, Obsidian was doing games for a specific audience, pursuing a creative vision over mass market, and I fear that'll definitely change, and the games will become much more "consolish", much more mass-market, much more driven on action and much less on story, characters, world-building and reactivity.
And worried that the games will become DRM-locked, Xbox/Windows only, meaning an end of an era for all of us who love our games DRM-Free and multiplatform (I'm personnally a Linux user, never owned any console, and not interested into installing (and paying for) an OS I don't like just to play games).
Is there any chance you'll still making DRM-free, cross-platform (including Linux and Mac) games even now that MS bought you ? I'm afraid not, but I wish I'm wrong.