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
I do love me some unique hardware experiences, but I hate that it’s inherently difficult to port them. There are a lot of wonderful games that have been stranded on consoles like the DS, 3DS, Wii, and Wii U.