If MS retains the rights to The Outer Worlds, that's an automatic new pillar IP.
Speaking of pillars.
I think an open world Pillars of Eternity game could be even better, and Sawyer has talked about how that's something the Eternity team really would love to do.
With TOW and PoE, MS would basically have its first party Fallout and Elder Scrolls equivalents.
I'd love for Obsidian, and maybe InXile alongside them, to rise up and directly compete with Bethesda. And the Pillars world would be really cool to see more fully realized, but I'd also be perfectly fine with an entirely new third world. If also love to see them do something more low fantasy, along the lines of Vampire the Masquerade.
Elder Scrolls and Fallout seem to be getting a little stale lately, potentially good Elder Scrolls Six not withstanding, so I'd love to see someone draw that direct comparison and put a little fire under Bethesdas bum.
I also think it's funny that Outer Worlds is going to predate Starfield, a game which it will almost certainly be compared to in the future by journalists.