The problem here is that an arranger doesn't just transpose a loop or adjust the 3rds or add 7ths, etc. for different chords.

Most arrangers can have an utterly different loop for maj/min/7ths/dims etc. Plus there's a fair amount going on out of sight to make sure instruments don't play outside their natural range, that if there are lines going on, changing to another key or chord doesn't make the pattern jump around like a jackrabbit, and there's some pretty complicated stuff going on to smoothly jump to the correct note WITHOUT RETRIGGERING THE NOTE if you play the new chord a few ticks late.

A modern arranger engine is a marvel of some VERY complex stuff going on to interpret the simple chords we play into musically accurate parts. I doubt that Akai (who've never really made a true 'proper' arranger) are likely to want to dive into something as complex as a brand new arranger engine, particularly as most people in the MPC ecosphere are only using audio loops, and MIDI is less important.

A tie in between Akai and someone like Korg would probably be the only way this might happen, and I just don't see that type of inter-company cooperation happening here...