One of the few limitations on the KPA is the limit of one effect loop. Might it be possible to design a small little box that has multiple sets of sends and returns and connects to the Kemper through one of its USB jacks? the little box would essentially just be an audio interface designed for the Kemper that would handle the AD and DA conversion. Then the KPA could just call up any one of this devices loops in any of the slots. Whatever processing power was needed to perform this could be built into this box, with the KPA doing nothing more than sending midi messages to it or some other non midi message that would tell it to call up whatever loop or loops desired. The user would simply spin the browse knob and select one of the loops just like it does the one wired effects loop that can be dialed up now. The user wouldn't have to worry about midi, as they'd simply see the four or however many loops as options to select in the effect type list. Perhaps it could be wired in such as way that if some of the loops were used consecutively in adjacent slots, it wouldn't have to go DA / AD again for those consecutive loops? Otherwise, of course each additional AD and DA would add collectively to latency; but users are likely not to need all the loops going at once anyway.
At the moment, if you wanted multiple loops, you could buy one of those analog multiple loops devices that are midi controllable. Of course, you're limited because you can only send midi messages on rig changes. Thus I have one of those decibel 11 devices for my overdrive pedals, which I've stopped using as I don't have the flexibility to simply send a midi message without changing rigs. (Whereas by using internal Kemper overdrive stomps, I can turn them on and off without leaving the rig.) The other issue is that those midi messages that tell the decibel 11 what combo of loops to engage don't travel if I copy the rig to a different performance slot.