One advantage Steam has is it doesn't need to win over the publishers and developers to release stuff on their new platform, it already has them.
I honestly think it's going to flop big time. As will the OUYA and Project Shield.
Who are they trying to convert?
XBox owners who know there's a new console on the way? Not a chance.
Playstation owners who know there's a new console on it's way? Not a chance.
Nintendo owners? I don't think so.
People buying new consoles? Not a chance.
PC owners? Gibe me a frikkin' break here.
As far as price goes, OUYA may have a chance if it's cheap, as a novelty for existing tech owners. But why if you can play Android games on your smartphone or tablet?
And no, smart cool stuff that works does not sell. Look at the Vita. It's going to have to be cheap to stand any chance.