As we all know, Nintendo likes to use new technology once it gets cheap enough to make sense for gaming. With the DS, they introduced duel screens & with the Wii, motion controls. They kept them both for the current gen but added to it.
3DS added the 3D, while the U added a Gamepad as a center of the system. Wii U still heavily uses Wii Remotes for multiplayer games though.
Next Gen will be here within the next few years, what will Nintendo keep, and what will they ditch? What would you like them to do?