The best discussion of "steam box" I've heard was the game informer show. Which stated the obvious that no one else seems to mention. The only way steam box is going to be a big deal or needs to be purchased is if valve commits its 1st party to the console exclusively. If not and I can just play valve games on my ps4 why waste money on steam box.
I also believe a good deal of the excitement around steam box is it force MS, Sony and Nintendo to step up there game, and games. The competitive field gets a little bigger and somebody going to be missing some lunch money.