At this point probably the smartest thing which Microsoft could do would be to adopt some Linux distro (perhaps OpenSuSE, which they already have some relationship with) and base all of their future development on top of it. At a stroke this would eliminate many of their security and malware problems, dramatically improving the user experience.
Windows remains prevalent, but at present as a software developer I'm not seeing much of a future for it, other than as a legacy system that I may need to support, and am recommending home and business users to move to other platforms (either Linux or Mac) whenever that's possible.