Modern gaming controllers owe a lot to Nintendo- Dpads, face buttons, shoulder buttons, analog sticks, vibration, wireless controller technology, touch screens, microphones, and motion controllers are all ideas for game control pioneered and popularized by Nintendo.
With the NX, Nintendo may be planning on doing something like this all over again, except this time, the technology that they seem to be looking at seems to be something that will greatly benefit and enhance hardcore games, as opposed to something aimed at mainstream casual audiences.
A new patent that Nintendo has registered for the NX seems to indicate that Nintendo is planning a new controller design that features scroll wheels on its top two shoulders. These would be like scroll wheels on a computer mouse, and presumably, just like them, they would also be clickable, doubling as shoulder buttons as well.
The possibilities that these would provide are endless- they could provide for quick hotkeying, quick item and menu scrolling, and more precision in action games.
You can see the patent drawings below- note that the drawings show a controller with a screen, but curiously, it seems to have only two face buttons, and it seems to have only two shoulder buttons as well. The actual controller itself featured in these drawings, then, is probably just a concept rendering, and the final product will differ.
Whatever it is, the NX just turned even more interesting than it was before.