I always wanted to do a keyboard/tablet combo (maybe they make these, I don't know).

The idea is a fully weighted hammer action keyboard with nothing else, such as the Arturia KeyLab 88 MkII, and add to that tiny LED lights above each key. And have a tablet computer which has a tutor, and it shows the notes but also a guitar hero like display of the coming notes, where the LED lights shine for where to press, and correction for timing and heaviness of press, etc.