I could imagine a future where Windows is just a proprietary DE over a Linux system. I don’t think it’s coming anytime soon because of the development cost it would impose, but I don’t see why they would go to such efforts maintaining a system they could get for free if the desktop user base keeps shrinking. They’re just too greedy not to do that. Even the backwards compatibility with Windows software is becoming a solved problem.
Aside from my above rant, the PC is definitely fast becoming an enthusiast/business platform. I opened a retirement account the other day through my smart phone!