All you need in a keyboard is to accept standard audio loops, all the editing can then be done using Melodyne and then loaded back into the keyboard. (All modern keyboards can have multiple Midi tracks per part, (Intro, fill, variation etc.) with the old 4 (Major, Min, 7th and min 7) track system being long gone, so manufactures can modify them to accept audio loops)

Obviously Hardware boards will require a jump in their storage capacity, but that’s not really a big problem to solve.

Bill