We know already that Microsoft is readying a PC specific version of the Xbox Game Pass. You can find out more on that right here. However, the company also revealed that they plan on bringing more of their titles to even more PC storefronts in the near future.
We already know that Halo: The Master Chief Collection is coming to PC via Steam and the Windows 10 Store. Today, it has been revealed that Microsoft is already planning to bring more than 20 Xbox Game Studios titles to Steam. This will begin with Gears 5 and the entirety of Age of Empires I, II, & III: Definitive Edition.
Microsoft says that they want to bring players together to create "a shared player community regardless of where they play." They say that the Xbox Game Studios titles will include voice and text chat, looking for group functionality, friends list, and cross-play between PC and console. Specifically on Windows 10, a lot of this functionality is built in to the Xbox Game Bar that they plan to keep adding functionality to as time goes on.
We know millions of PC gamers trust Steam as a great source to buy PC games and we’ve heard the feedback that PC gamers would like choice. We also know that there are other stores on PC, and we are working to enable more choice in which store you can find our Xbox Game Studios titles in the future.
We want creators to be inspired to bring their best content to Windows 10, and we want Windows 10 to be the place where gamers come to discover their next favorite PC game. We recognize that Win32 is the app format that game developers love to use and gamers love to play, so we are excited to share that we will be enabling full support for native Win32 games to the Microsoft Store on Windows. This will unlock more options for developers and gamers alike, allowing for the customization and control they’ve come to expect from the open Windows gaming ecosystem.
Not a fan of the MS Store, i haven't picked up the latest Forza Horizon yet so now i'm inclined to wait and see if it comes to Steam.
UWP is a neat idea but it locks developers into the MS ecosystem, which is why the vast majority of titles in the MS Store are mobile games, there's also the issue of how its games are virtually un-modable, because while the big titles like Gears and Forza are pretty well optimized and perform very well for most, it's always nice to be able to tweak a PC game to get it working the way you want.
MS have every right to sell their own games on their own store, but Steam is a better store, in every single respect, this is a good move.