Probably it would be possible but whether it would be economically feasible? I have a multishot back and the difference between MS and Single is enormous, IMO.
The only multishot-like DSLR currently available is the Sigma SD14 (and its predecessor). Which is not so much as a multishot but has a sensor type that doesn't interpolate the colors (Foveon).
I would expect more manufacturers to use Foveon (or technology like that) before we will see MS DSLR's.