Given many new handhelds coming on the scene and general disinterest of Microsoft to support the market, do you think SteamOS will take place of default OS the same way Android did on phones some time ago?
Windows, currently, cannot handle everything Linux can. Linux also has a massive software support advantage, running on vastly more hardware and architectures than Windows does.
Linux has already been given to the masses. People use it every day in super user friendly ways; they just don't realize they're using Linux.
The only reason people use Windows is because they don't choose it. Imagine if every PC sold had a Linux option and a Windows option that cost an extra $100. What do you think people would buy?
The same hardware running Linux will easily outperform Windows (especially at the most common end user tasks like web browsing) by a long shot. In a few days NTFS turns 30 years old FFS (LOL).
Any given hardware accessory will "just work" when plugged in to a Linux PC but Windows will require a special driver that you have to go out and find on your own at the vendor's website that will be bloated AF. It'll also reinstall it if you change the USB port LOL.