Assuming the NX image is of the Console Controller (seems like the logical bet), I'm more interested in what it means for the handheld. We can kind of assume.
Dual Screen Formfactor. You aren't going to make the console a 2 screen device and leave the handheld single screen if you assume any sort of porting/cross compatibility at all. Etrian Odyssey can continue unabated.
Capacitive Touch. This one is a positive and negative. Capacitive touch feels significantly smoother and better than resistive, but for the simple functions the DS subscreen has, resistive is almost better.
Customizable buttons seem potentially more interesting on a handheld then a regular controller.