Are you so sure about that?
I bet that is just going to be another Microsoft huge mistake and failure.
They keep copycat Apple in the worst possible way and now they think to be able to force developers to publish on their store instead of Steam for PC games. That is not going to happen.
Just like the whole WindowsPhone thing got rejected by both developers and customers rather quickly. But they keep doing the same thing over and over and Windows10 is filled with all kind of spyware which makes it unusable unless using a 3rd party tool to disable all currently known Microsoft-phone-home nonsense spyware/malware in the OS.