"client platforms become less critical in the Web app age"
Are you sure? Mobile platforms shown exactly the opposite - native applications for the platform. Quicker, and far easier to use.
Web apps are still very clumsy to use when the UI becomes complex enough - and UWP tryintg to ape web apps made desktop applications clumsier too - one of the reason developers of complex application kept developing Win32 applications.
When MS will lose the desktop advantage, really, why use Windows just to run Google's browser - given they gave up on IE too? Azure will follow - Azure is going well just because there are billions of Windows desktop systems which rely on Windows technologies.