A programmable sequenceable compressor would be way cool.
multiband, with dual tube-driven stereo input preamp stage
not one but two sidechain inputs.
also what about a Machinedrum Userwave III, same size and same colour scheme. Still 12 bit, but with more awesomeness. with 16 audio sample/synthesis/ctrl tracks, and a 4 Midi Track sequencer with 1 cv sequencer on the side. lexicon-style reverb, bonus global analog filter stage.
optional addition, a programmable sequenceable control surface rhythm pad. same size as the drum machine, same colour and material scheme. different layout though, more like the Digitakt, except for a rhythm pad. large dial rotaries along the top, a t-bar and an x-y pad, 9 faders and 12 rhythm pads.
one circular pad in the middle, crowned by two triangle pads with an inverted triangle between them, four oblong-semi-circles adorn each side, and a horizontal oval rhythm pad below the central circular one.
make it possible to program-in rhythm feel by having the famous Elektron sequencer playing in sync, p-locking the velocity response of each pad in real time. And so many more options to sequence regarding the rhythm pads.