I think the strongest competition is actually other Windows versions: People are usually fine with the Windows version they know and use - Microsoft already had

I think the strongest competition is actually other Windows versions: People are usually fine with the Windows version they know and use - Microsoft already had to drag it's users kicking and screaming to update from XP to 7, then later from 8 to 10. I feel they'd have to up that kind of pressure by a lot to get people to switch not just to a new version, but now even one that requires a subscription. So if this ever becomes reality, I expect a massive campaign of FUD, dark patterns and deliberate incompatibility to get people to leave the old versions.