The fact that Valve has stayed "small" might be the singlemost reason why they're actually pushing for alternative gaming options.
Steam for Linux and the games that come with, do you figure that'd be the case today if the company had sold out like for instance Blizzard?
Steambox/Piston? Yeah, no. It's a novel idea with some potential if they can get the module upgrading right along with a stable whatever Linux distro they end up going with, but no stakeholder og board of Scrooges would sign off on that stuff.