Same story here, like laptops never replaced desktops all those years, same again tablets will not replace neither desktops, neither consoles.
Tablets are pretty powerful sure, maybe in a couple of years we could connect a tablet in a full HD tv and it will be able to play games at 1080p like a gaming computer does today.
But TVs and monitors are moving forward as well, and they will start making standard higher resolutions that a tablet could not possible be able to handle.
We are technologically very far away from devices "one size fit all" and we will always be, because technology is changing as we speak and is moving forward.
So there will always be higher demand on computing power than what a mobile device will be able to provide, because it have to stay mobile as well (that's it, until we discover batteries of endless charge).
Just my 2 cents.