Both Luke and Maul fall down long shafts and somehow survive, and both were arguably in worse shape than Palpatine-Luke lost his hand, Maul his lower body. Palpatine just got tossed pretty much. Granted, the Death Star exploded shortly thereafter, but it's possible I suppose he could've escaped using some other method. Or maybe all along he's somehow survived in the wreckage.
It's always been said that the big rush of energy that comes out of the shaft is simply all of Palpatine's dark side energy being released upon his death. What if it was something else all along? Maybe some other force power that helped him somehow survive? We've also seen other force users survive pretty large falls before (Take several parts of AOTC for instance).
Know it's kind of a goofy theory but it does seem to have a bit of precedent....