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
Wireless transmission latency is good enough for pc players connecting to oculus headsets. Besides, if this is just a wishlist, I would hope that nintendo keeps traditional docking as well if you are playing a latency critical game or want to use a pro controller instead of the console itself as the controller.