So, I only recently got and started playing Super Mario 3d World.
The game is fun.
If I were thinking of a mobile and console way to play the game. What if the console version of the game was the regular levels and the mobile version of the game was the Captain Toad levels?
Smash bros is another example. You play the single player at home, or you could play multiplayer on the handheld or at home.
Maybe the handheld system is basically another system, but your games library is combined, and depending if your out and about you get a different experience.
In game development this really only works for Nintendo who already does this, but it has the added benefit of gamers who have a more focused Nintendo and a more flexible library.
My biggest question though is "How much is this thing going to cost?", and "even if its the best thing since sliced bread, will the public perceive it that way?"
The Wii U has some convenience advantages over PS4 and Xbox One, but nobody seems to care.