Running X server applications on Windows could be done from the first inception of WSL (shameless plug [0]). You essentially run Xming, then point your environment to the Xming display server prior to running GUI applications. You can even run a web browser like Firefox.
I actually use this for developing bare-bones x86 assembly on qemu: qemu runs as a X server application. In fact, my entire build pipeline is based on Linux tooling but I actually develop on Windows.
Windows Vista to Windows 10 as an overall platform made many bad decisions, but these are mostly from terrible product planning and UX. The internals (kernel, comprehensive HAL and huge driver library) are the only existing, solid alternative to Linux (and to a degree bsd) that does many things uniquely from their UNIXy counterparts.
As a die-hard Linux user I would be very sad to see the loss of a different platform that explores unique ways of doing things. A near-total monopoly outside of research projects isn't good for Linux, or BSD.
Why would they want to do that? The way they are doing things now allows both windows regular users to continue working without noticing any change and people who want to use Linux tools happy at the same time.
Counterpoint, if they're willing to build on open source, they have the work of a huge team that's been working for years in terms of the WINE project. I feel like Microsoft has the resources to make that work really well.
Technically they probably could... but whats the point?
I would think that the cost to move all that already exists on windows to a Linux kernel would cost many millions and don't see how it would make its money back over even a decade out.
It only makes sense to invest such a large amount of money if Windows was the future of Microsoft which is not where the company is aligned anymore.
If Microsoft was to adopt Linux it will likely be for a new OS (say for wearables, IOT, server or embedded), rather then existing ones, as in this case it would likely be cheaper then building from scratch.
On the one hand, I can see what you're saying. On the other hand it seems like Microsoft has been caring less and less about breaking things lately. Personally, I dread this future because it will mean that Linux Desktop has won, not by being actually good but because everyone else just abandoned personal computing as a serious goal.
