A smart tv isn't a tablet, Xbox 360 isn't a tablet, ps3 isn't a tablet. Yet they all have apps.
Please elaborate on what your definition of a app is, because to me, i don't see the need for things like Facebook, Twitter, eBay, instagram and so on when you will more then likely have a internet browser with full controller and keyboard/mouse support.
If you mean apps like Netflix, Love Film and so on, they will come, maybe not right away, but i really don't think that will make or break a sale.
What will make or break this console is accessibility, as in can the average joe pick it up and use it and how quickly and easily the games are distributed and how they play.
What the hell has two yearly gfx card refresh or i5/i7 got to do with anything.
Steam console by its nature is liekly to be a different market to current consoles. Mainly it's focused on pc gamers, not console gamers. I wouldn't expect it to have much impact on conventional console sales and as said be more aimed at us pc gamers ditching or adding to a desktop.
My point is it'll be vastly superior to consoles because of the constant upgrade ability of the device, if you statically force the console to say come with a i5, 8gb ram, 120gb SSD and then say a 7970, then you have you hardware static requirement, then all you do is make the graphics card hot swoppable and you then have a constantly self sufficent console that is upgraded graphically at the whim of the consumer and not the console makers.