Possible? yes. At real-time speed? I doubt, but 1fps or 0.5fps should be doable. Image quality? I doubt it will compare with a proper long exposure, but it will have a little more DR and it can also work for long exposures in daylight.
But if anyone gets bored and wants to code something cool, start tweaking the silent picture code. I actually have a half-working patch written a few months ago - it only needs some display filter trickery, fixing the vertical banding, and optimizing it for speed:
http://a1ex.magiclantern.fm/bleeding-edge/silentlongexp.patch
