Who knows, but "Reason # 4: They'll be going up against already well established names". The same happens with Sony & the first playstation, and they won the generation. Valve has a renown thanks to its digital platform.
True, but Sony's only real competition at the time was Nintendo, and they're main advantage was loads of third party support, something that Nintendo didn't have. Sony did what they still do to this day and marketed the console as the one with a multitude of games to play, while Nintendo just kindof marketed... well... Nintendo. Valve doesn't have that advantage, especially not in the console buisiness. Clearly that ball is Sony and MS's court and it won't be leaving anytime soon.