It seems that the need to use a Microsoft operating system will decline with the improvement in open source device drivers and web services for applications.
Why worry about Microsoft operating systems as a non-user? Well, the spam viruses on Windows affect all of us. I have not had a Mac virus for at least 10 years (sure, you could joke that nobody writes apps for the Mac any more =), but my email inbox has seen the effects of the Windows worms.
And of course, I am an indirect user of Microsoft servers. And that can be another source of concern. Microsoft is a global monoculture and is therefore subject to catastrophic collapse. The resiliency of critical computer networks might suffer if they migrate to a common architecture. Like a monoculture of corn, they can be more efficient, but the vulnerability to pathogens is more polarized - especially in a globally networked world.
When will the desktop Linux swap out occur, as it did seamlessly at Apple with the XNU kernel in OS X?