The success of the SteamBox will be measured by how it affects the success of the Steam platform against its costs to Valve. How should they go about it? I'm not sure but Valve is a smart company and I'm 99.9% sure they certainly have a plan as to how.
Exactly, that was sort of my line of thinking. Making Half-Life 3 a Steam exclusive would be the ultimate marketing tactic to bring console-gamers onto Steam.
I don't think that makes a lot of sense. The Half-Life franchise is predominantly identified with PC gamers with the only massive exceptions being those console gamers who really attached to The Orange Box. Making Half-Life 3 a SteamBox exclusive would cause more outrage than sales from PC gamers too imo. Customers have invested a large stake in their rig and the majority of those customers will continue to do so unless SteamBox offers something that conventional towers never can.