(Disclaimer: Don't take these as leaks. This is a recap of rumors and whispers ... with a bit of wishful thinking.)
've heard credible rumors that despite winning awards for its single-player title Hellblade, Ninja Theory is, in fact, working on some sort of multiplayer game, in a similar vein to For Honor or Absolver. I'm not sure how true that one is, so we'll have to wait and see. I've also heard that Rare is working on another multiplayer game, alongside Sea of Thieves, which may come as a disappointment to those expecting a return to Banjo Kazooie or Conker. Still, there's no reason Rare wouldn't be able to outsource and contribute those IPs, similarly to what they're doing with Battletoads and Dlala Studios. I expect we'll see the new Battletoads in some form, even if it is brief.
Halo Infinite has been rumored to be taking on some form of "RPG" approach to its gameplay, but I've heard that any progression systems are soft at best. You're not going to be grinding stats, put it that way.
Microsoft will show off a new Forza Horizon 4 expansion at E3 2019, and I've heard that rather than being location-based, it will be another brand-oriented partnership in a similar vein to the Hot Wheels DLC. If you were a fan of Hot Wheels, you should be pleased with what Playground is bringing to the table here, if what I've heard is true.
We're expecting the new Xbox consoles to come with an all-new OS, based on Windows Core OS, which we've been covering for some time now. Expect an all-new dashboard based on the Fluent Design System, with the speed and fluidity at the forefront.
As for new studio acquisitions, I haven't heard a sliver of credible information. There have been suggestions Microsoft may acquire Relic from Sega, to help elevate the Age of Empires franchise. Rumors (likely made up) have also pointed towards a range of other independent smaller studios, including IO Interactive, Asobo Studio, and even Crytek. I haven't been able to drum up anything I'd call concrete on this front, but typically these talks are at the highest level and aren't easily leaked save for occasional instances of public company documents.