Board Thread:Spoilers!/@comment-27979095-20160321180132/@comment-5106672-20160321190758

Well, initially Hercules was a demi-god headed to Olympus to become a full-fledged god; now he's in Olympus as his afterlife reward for finishing his unfinished business. What comes next depends on whether his untimely death has affected the deification process: if he has become a full-fledged god, he might very well show up again someday (we don't know how powerful gods are exactly, but chances are they can go across realms); if he's just a regular dead soul in heaven, he may not.

Side note: in the original myth, the sources are conflicting. According to the Odyssey, he died and was in the afterlife with regular mortals; according to his widespread cult, his death as a mortal (long after the Labours) let him ascend to Olympus as a god and he even married a goddess, Hebe. There's even some middle ground according to which his mortal coils descended to the Underworld and were seen by Odysseus while he ha actually ascended to Olympus as a god. So anything's possible in the OUAT continuity, really.