Sure, but the fact that the desktop became less important compared with mobile/web doesn't actually solve the problem of Microsoft having a monopoly on PC operating systems. Gnu/Linux is almost unusable for non-techies, not because it's deficient, but because almost all third-party software and hardware is built with Windows in mind, because that's what people get when they buy a computer.

In a well-functioning market, all you would have to do to beat Microsoft would be to make a better operating system. In the current market, to beat Microsoft, you have to make a better operating system, target a new category of device, and own one of the biggest companies and several of the biggest websites in the world.