It'a also why they're updating Windows 10 steadily to support integrating with Android deeply as well.
Not to mention they've working on their Linux subsystem for Windows (WSL), cross-platform services and apps like VSC, buying Github, Xamarin, etc), and also porting/improving macOS apps like Visual Studio and Office on macOS.
Microsoft's cash cow is now their services and why they're turning previous Windows and Office cash cows into subscription services. I suspect they plan to do an overall Microsoft service; get Windows, Office, OneDrive, and Surface for a monthly price.
Which is what I suspect Apple will do as well as Google; all of them will do software+hardware bundle subscription service. Imagine paying 100$ a month to get latest hardware and software all the time.
If they were to open source alternatives to Google's Play Services and give developers a low or no cost app distribution method, I could imagine them doing a lot of business hosting instances of those service layers on Azure.
Developers get lower costs and Microsoft picks up more cloud share.