XY Pads instead of knobs or faders! Ahh
I immediately thought of Lee Perry and this guy called Allan Shacklock. Allan worked at Abbey Road in the 60s and when he listens to Beatles or Pink Floyd, he “air faders” instead of “air guitars”.
The only feature I would want on a mixer, besides run of the mill stuff, would be maybe built in controllable bit reduction across a bus, perhaps an xypad like a Moog Voyager, and nice sounding analog preamps that you can overload the fk out of for some “Savvoy Truffle” type sounds. Like this guy