They'd practically be telling all their casual, professional, and enterprise userbase to not update. Their prior support for win32 has locked them into it, even if they want to leave it
I think they are realizing that it's holding them back and I suspect they will be less afraid of breaking things in the name of progress.
When I updated my laptop from Windows 7 to Windows 10, it just uninstalled the things it thought was incompatible (a Cisco VPN client was the big problem).
In fact, the sneaky and slimy strategy that they used to get people to update to Windows 10 feels almost like contempt for customers that don't want the things Microsoft is pushing.
Is the PC gaming market a big one? Is there an opportunity here for Linux to become a gaming contender?
Current state is that 25% of the Steam library is Linux-compatible. That's about 2500 games, so definitely enough to keep you entertained, unless you're the type of gamer who always has to play the newest AAA titles.
With Vulkan slowly picking up adoption, this will probably increase even more rapidly in the future, too.
Next thing is that Vulkan as well as DX12 make it so that drivers for graphics cards will be much smaller and therefore the resulting drivers will be much less likely to be broken, which has been a big problem on Linux in the past.
But Nvidia has now pretty good Linux drivers anyways and AMD has recently started investing more resources into it. Among other things, AMD open-sourced their drivers, so now the Linux-community can help to fix up their drivers instead of maintaining an own driver.
I also figure that the growing machine learning market gives a good incentive for Nvidia and AMD to have good support for Linux, so that should translate back to the desktop, too.
The only problem is that all of this can serve as reason to not avoid Linux, but unless Microsoft really does continue making such great arguments against using Windows, we won't really see many people change operating system...
When a title is Linux-compatible, does that mean it works flawlessly? Does it use Wine?
I don't know, if Valve requires anything for that, but it's specifically not the percentage of titles which you can get to work through any combination of black magic. It's the percentage of titles where the developers offer you support, if it doesn't work on your system.
And I know that some of those games do use WINE internally for the port, but it's properly pre-configured in a wrapper and should work just as well as a native Linux-game. So, you don't need WINE installed separately on your system for those.