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
But the right joy-con already has a IR-Camera.
…On the bottom. One on the top that can work in tandem with some sort of sensor bar would have to be squeezed in above the R and ZR buttons.