timppu: Well, I was actually more thinking about MS possibly just losing interest in an open-PC OS, and more concentrating on their closed tablet-like devices, game consoles and Azure/streaming.
It is interesting to note how less and less dependent even workplaces are on Microsoft. It used to be that you HAD to use Windows and MS Office and whatever, but I am now doing most of my work, even desktop office stuff, on Linux, Libre Office etc. Two MS products I still occasionally need are Skype and Teams... but nowadays even they work just fine on Linux. Even Outlook (e-mail and calendar) has mostly lost its meaning for me, I use other clients and tools for e-mail an calendar.
Now, I am unsure if there are still people to whom e.g. LibreOffice is not an option but they HAVE TO have MS Office Excel, Word, Powerpoint etc., but to me it would appear even corporate world is less and less dependent on having Windows. Well, ok, I guess companies pay for support that they receive for MS products, so there's that.
I doubt that since they would be shooting themselves in the foot. They can do both, no reason to let go of the market dominance they've built up for themselves. Windows is the option for gaming, so there will always be demand. Linux definitely has its uses, but no matter how much anybody argues, it is not the best option for gaming.
And from experience, I still know a lot of places and companies which are still on Windows 7. Microsoft even offered paid extended support for it exactly because so many companies had systems dependent on it and couldn't/can't/didn't want to upgrade. I don't see this changing in the near future and my guess would be that it's going to take 10+ years to change in a noticeable way.
Same with Office, I know tons of places that are working exclusively with Office. Even some schools still only accept inputs specifically in either docx or xlsx. My sister for example had a problem uploading her University work because they only accepted Word documents and she didn't have Office.
And overall, considering that there are many completely free alternatives, yet the monetized Windows still dominates the market, I think their position as the top dog is pretty safe for years to come.