I don't believe that Apple will produce a truly converged device (a la Surface) until they can create a device that can run both OSX and iOS and fully implement Continuity. Without the keyboard, it runs iOS... with it, OSX.
Now that will be something that certainly peaks my interest and possibly worth buying. If battery technology can get to the point where plugging in an external keyboard automatically charges the battery on the futuristic version of this iPad concept (because OS X would definitely be less power-efficient than iOS) and switching between iOS and OS X would also be detrimental to battery life (because restarting is not good for battery life). Interesting stuff!