Problem is people that like PC games already have a PC usually, so naturally that is their target audience.
Who is going to buy a Linux system that doesn't offer all the features a normal PC has if that person already owns one ? Sure there might be those unknowledgeable ones that don't know that you can easily set up your PC to your TV and have that couch experience. Those will be amazed at first, but I'm sure even they will realize that genres like RTS, Manager games, MMOs, Counter-Strike (looking at the most played Steam games) are not as good to play with a controller, which means that the couch experience is ruined (at least to some degree).
Overall there is far too much (internet) hype for this piece and the more it gets the more unlikely it will become to match expectations.