I remember when Apple introduced the Mac App Store and people heralded it as the downfall of third party software on OS X. There were pundits who swore that Adobe products would cease to exist or massively lose functionality to fit inside the app store model.
It turns out, none of those things happened. The Mac App Store is almost a wasteland, and people still sell software for the platform outside of the store.
A fun counterpoint is iOS, though I would argue that since it has been a closed ecosystem since day one, it's a completely different animal.
Final thought: Giving away Windows 10 and future updates for free has a cost. Microsoft doesn't make nearly enough from Epic Games or Steam or any other software provider to compensate for all of the license sales it makes, and enterprise software isn't growing fast enough to sustain their investors' expectations. And furthermore, Epic just made their OWN games client (which will lead to their own "store"), so really this is a corporation asking for regular customers to go to bat for them against a bigger corporation. I don't know about most of you, but I can't really get that emotionally invested in their business squabbles.