Steam OS sounds incredibly Asinine. I have no idea why everyone's losing their minds over it, especially when you consider these facts about it:
1.) Out of the 2k+ titles on steam available to windows users, only 400 of those titles are available on Linux, and roughly 10 of those are AAA titles that were released several years ago. The rest are mostly titles no one has ever heard of or bothers to play.
2.) PC game developers are very unlikely to split resources to develop a Linux version of a new AAA title.
3.) In order to take full advantage of Steam OS... you still need a windows PC to wirelessly stream the games. Think about that for a sec, you're buying a $400+ Linux based computer with extremely limited access to the steam library, just to stream games from a windows based gaming PC you've already spent money on.
4.) Consoles (360, XB1, PS3, PS4) offer a superior experience for the living room, without having to create a complicated setup.
5.) Steam OS itself will be no replacement for windows. It will mostly be a closed content delivery system for Valve.