On the other hand, there have been cases where the new publisher got the reprint rights after the license changed hands -- for instance, when Del Rey got the Babylon 5 novel license away from Dell, they reprinted at least two of the Dell novels (the ones that were still counted as more or less canonical). Similarly, Dark Horse has done reprints of Marvel's '70s-'80s Star Wars comics, and IDW has reprinted Trek comics from multiple other publishers.
Didn't Pocket itself do that with Mission to Horatius at one point? Or am I remembering wrong?