It seems like I forgot the most obvious output when I did my analysis of this rumor… The USB plug! I cant believe I forgot it! It has enough bandwidth to carry a RAW signal to the hypothetical module. It would basically be the same thing as when shooting in tethering mode, except for video. Suddenly, such a product looks much more viable (and still as desirable!).
Of course, we have no idea if it is remotely possible from a technical point of view and if the rumor is actually true. Lets just hope it does not come from the same guy who said a 24-70L2.8IS would come soon!