I have had the same idea about martial arts. Not sure it is possible. In dancing you have at least some symmetric patterns and rhythm, in martial arts you have even more stances, rotation around more axes and arrhythmic moves.

good dancing like good fighting isn‘t mechanical either, it is good because it relies on little imperfections. Just like MIDI files cannot replace a concert pianist.

In the end I think motion capture of extremities along with some easing of paths and compression of point-clouds (think bezier curves) might be more worthwhile than a notation.