I'm personally not interested in this, but the NX should have achievements. I believe the most recent Mario Party game had something like that.
I would also like to be able record gameplay to upload to YouTube like PlayStation 4 and Xbox One. Being able to upload replays of Mario Kart 8 and Smash Bros was a good start imo.
Lastly, all digital should be linked to a person's account so that if the system ever breaks down, a person could easily get another one without worrying about losing everything.