Sorry folks but this plan has about a 10% chance of winning market share:
1. you've got new shiny consoles coming out in less than a year. Console folks know those names and brands. They will have no idea who "steam and Valve" are. That's a problem.
2. The Valve box will be underpowered versus the desktop PC's of many gamers because it MUST compete via price. AND It will have to compete with the new $399 consoles of 2013. And many gamers already have PC's.
What consumer is Valve aiming for exactly and are those consumers numerous?
I like the idea Valve is presenting but in reality it will just be another low-power device that underwhelms most gamers. They will vote with their wallets.