[usrusr]

With a defined artificial latency headroom and a message parameter to (partially) override that latency it would be possible. With reasonable low maximum concurrency and a very high bandwidth/message size ratio the required extra latency could stay well within the range of centimeters at speed of sound (a very high bandwidth/message size ratio would certainly also lessen the cost of not taking that feature).

The next roadblock on the way to truly concurrent chords would probably be controller readout. I know nothing about how those are typically implemented, but I strongly suspect sequential readout.

[PaulDavisThe1st]

The existing spread for a typically chord (triad) is already not audible (despite the claims of some people who refuse to double blind test it).

Changing MIDI to have "defined latency" is a fundamental re-engineering of the entire protocol.