Looks like someone didn't read the full story. These are for the user that desires the high-end hardware. Not low-end like consoles. There will be Steamboxes aimed there too.
The low end boxes won't be price competitive with consoles in 2013-2015, that is the big boys territory, big budgets.
Maybe in a couple of years they will start to challenge but by then the next-gen consoles will have already established a strong enough install base so as not to be worried by it all.
Taking off the shelf parts and selling via OEM is not going to give you a better price/performance metric compared to a dedicated console manufacturer who is razoring the product. When those parts are finally ready to give you that advantage, you're going to be cumulative 40mn behind in the race and largely irrelevant.
These things are not mass market. There is nothing about them that will ever make them mass market. Multiple hardware configurations of the kind you find in PCs is confusing and will never be mass market for games. These are niche and appeal to the same niche as the PC gamer today. As a PC gamer, I wouldn't buy this, why would I?