Routers, phone, set top boxes, top boxes...and guess what? None of them use the command line. Like any operating system kernel, Linux can be skinned to do anything.
It can't be skinned to suddenly have a huge library of AAA games like you can find on a Windows-based gaming PC. How do you skin Linux to do that?
The problem with your above post is that there is a lot of "imagining" required to get to the outcome you desire. Since we are talking in circles here, why don't we revisit this thread in a year or two and see how the SteamBox rocketed to success? My prediction is that just like other similar attempts (at Linux gaming), it would once again be a big fat fail.