But maybe they have?
Windows+Xbox was less than 10% of their revenue. They note it is in decline and looking at the bulk of the revenue, not much of it seems vulnerable to people just not caring about Windows. Their cloud business is the bulk of their business and it is not particularly sensitive to OS selection on desktops.
One might argue that Microsoft 365 is at least in part tied to the Windows platform, but in my experience non-Windows businesses still buy into it, even if their users are largely relegated to browser based access only. At this point they have businesses so scared of not having it, they would have it even if they were just phones and ipads. You *never* want to risk a customer or partner sending you some office document that can't be read, and whether or not other options are actually capable hardly matters in the face of the *impression* that anything less than Microsoft is a risk.
The biggest unknown that I think would be sensitive would be the 'consumer cloud' portion of Microsoft 365. That's going to be mostly people who clicked through the Windows built-in advertising for using Microsoft 365 as storage and backup for their laptop and add-on software from device sales that prod users to up-sell to Office. The release doesn't make it clear what the absolute number there is, but I seem to recall hearing that's actually a pretty small number too.
Microsoft is primarily a cloud and Office company now, and I'm wagering the markets have largely already accepted that.