Comment by ChuckMcM

I was thinking more like the burgeoning mechanical keyboard business for computers. If the mechanical structure was there your could provide arbitrarily low latency (some of the high end 'gamer' keyboards are sub-millesecond). Given the physical system you're modelling (Harpsichord, Piano, Etc.) all of the computation vis-a-vis the velocity can be computed while the key is moving and delivered when the key is "down", after touch on a per-board basis is easy, per key basis doable with more sensors. After touch doesn't have quite the latency requirements either. With these 25 cent M0+ 45MHz processors you could put one on every single key and 88 keys would incur like $88 cost for electronics.