To be honest, Linux as a desktop environment is already more usable than many people realize. People kept expecting a Big Bang where someone would put out The Release That Solves Everything, but what happened instead is that it just kept creeping up and creeping up. A similar thing happened to Linux gaming; Valve never put out a big Here's Linux For Games release, it just crept up and crept up to the point that it basically runs my entire library, and single-player gaming is now to the point that anything that doesn't run in Linux is the exception, not the rule.
And Microsoft's problem is that if they let this happen, they're going to be in a world of hurt when they decide to get in gear and fix it, because of their reverse compatibility support. Fixing all that up and trying to make everything go fast is going to be hard with all these systems interacting with each other. While we Linux users may piss and moan about systemd transitions or all the audio transitions, in the Linux world, as new subsystems come in, the old ones actually go away, and it isn't dragging anywhere near as much reverse compatibility baggage around. Helps that there aren't any project managers to demand Windows LDAP for COM Apartments Over Embraced And Extended USB to be jammed in to be supported 10 years later because one big client uses it and that mean the rest of us get to be running a WLCAEEUSB service on our computers for the next 15 years, causing occasional mysterious crashes when it spuriously grabs a USB device.
It seems to me Microsoft is in grave danger of walking itself into an MBA trap, where investement in Windows doesn't pay off this quarter so they don't, repeat for 15 or 20 quarters, and then waking up one day and realizing that one quarter at a time they threw away one of the most useful business positions in the history of the world.