This is a weird one, but I’d love to see a reimplementation of the sensor bar. The gyro controls haven’t cut it for me. I like how the Wii U game pad had the sensor bar built in to the bezel. The real engineering nightmare would be squeezing IR cameras into the top of the Joycon
Haven’t seen this mentioned yet, but I want to be able to put my save files on the SD card, not just games. I have crappy rural internet, so backing up save flies to the cloud is painful.