Microsoft is focusing all its attention on Windows 11, and even though Windows 10 still works fine for now, support will end in October 2025. Windows 10 is now taking one of its first steps to retirement.
Microsoft sells licenses for Windows 10 and Windows 11 on its online store, but the listings for Windows 10 have been updated to say that they will not be available after January 31, 2023. Past that date, you'll only be able to purchase a Windows 11 license. Microsoft told The Verge in a statement, "an update was made to the Windows 10 product page to ensure customers have the latest information on purchasing options for Windows 10."
The end of Windows 10 sales from Microsoft is a milestone towards the operating system's retirement, but it might have a minimal impact. Windows 10 licenses are also sold through stores like Amazon, and it's not clear if those listings are going away anytime soon. Both operating systems appear to use the same licensing system, at least for now, and some people have reported success with activating a Windows 10 PC with a key designed for Windows 11.
Activation keys for Windows 7 were available for a few years after Microsoft itself stopped selling them, but mostly through OEM key resellers of dubious quality (and legality). It's possible the same ecosystem will crop up for Windows 10, especially since many PCs on Windows 10 are blocked off from (officially) upgrading to Windows 11.