Microsoft repeatedly tried to assure fans that they've got a number of unannounced exclusive titles coming down the pipeline.
Considering that Microsoft's internal studios are all pretty much busy on known games (Rare with Sea of Thieves, The Coalition with Gears of War, 343i with Halo, Undead Labs with State of Decay, Turn 10 with Forza Motorsport and Playground Games with Forza Horizon), the company behind Windows and Xbox has two main paths to pursue: building new internal development teams from the ground up and making deals with independent studios to develop exclusive games.
Obviously, the former option takes more time to execute, which is why the latter option must have been quite attractive to Microsoft executives. This was recently confirmed by Obsidian Entertainment's co-owner and Chief Executive Officer (CEO) Feargus Urquhart. He was interviewed by Eurogamer on Stormlands, the Xbox One exclusive Obsidian was developing with Microsoft before the project got canceled.
When questioned by the interviewer with regards to the difficulties that independent studios like Obsidian have finding work now that big publishers try to do everything internally, Urquhart replied that Microsoft is looking to work with indie studios.
That doesn't necessarily mean these won't be big budget projects, either. There are mid-sized independent studios like Obsidian or Ninja Theory which are more than capable to create an AAA game, with the right budget.
We probably won't get any major announcements on those upcoming exclusives from Microsoft in 2017, given that convention season is now basically over in Western countries. E3 2018, however, seems a safe bet.
As to Stormlands, Obsidian tried to pitch it to other big publishers like 2K and Ubisoft but didn't have any success. Still, they managed to salvage some things and rework them into Tyranny, the real-time cRPG published by Paradox Interactive which recently got an expansion.