I dont see how steam machines will succeed, i think it will be one of the biggest flops in gaming history. The pc gamers wont see a reason to use steamOS which will limit your pc game library segnificantly, there is no point for them to build a dedicated steam machine which is a waste of money if you allready have a rig.
Hardcore console gamers wont care because like i said the smaller library, and this OS only supporting digital games makes people rather to switch to just the pcs instead of this. I dont see devices not supporting physical media as consoles, by that logic everything that has a controller attached to it is a console.
The casuals wont care because there are like 20 different version out there which will confuse the hell out of them. Steam machines are also more expensive than consoles dueto not being mass produced and not by the same company who runs the eco system.
