Windows LTSC already exists, but Microsoft, in all their wisdom, restricts it to enterprise licensees only, and seems to actively discourage using it as a desktop OS. The first problem is of course fixable with some KMS server shenanigans, but the second can be kinda painful when it comes to keeping drivers up-to-date, installing apps that rely on features LTSC excludes (and doesn't provide an easy way to install manually), etc.

I've often said that if Microsoft had just iterated on Windows 2000 forever I'd probably still be a full-time Windows user. If Microsoft had maintained an LTSC-like Windows variant that was installable from the normal retail installation media and with a normal retail product key (at the very least Pro, but ideally Home), that also likely would have kept me on Windows full-time instead of switching to Linux as my daily driver.