I think Nintendo makes great games, a way they can also make their games stand out if they went 3rd party would be to make a proprietary controller with their games.
They already push most of their games now to utilize the gamepad/tablet. If they did the same thing by making an 8 inch gamepad bundled with their next Mario for PS4, Xbox, and possibly Steam. the cherry on top would be if it was also capable of remote play.
I think they could end up being on of the biggest most successful third party developers easily.







