I don't think we will see another O.S. update for the Prophet 12,6,OB6 or Pro 2 again.
I agree though about MPE in general though. I'd love to see Roger come out with a box (similar to the Adrenalinn iii) but filled with MPE supported sounds (Slide and jazz basses, sax, violin, harmonica etc).
That being said I'd also like to see Roger and Dave collaborate again on an actual synth that has MPE.