One of the recurring themes in the third season of Once Upon a Time is the prophecy that Henry, the boy who helped Rumpelstiltskin reunite with his son, will ultimately be the Dark One’s undoing. Now, you and I both know that “undoing” doesn’t necessarily mean “death”, but the characters in the show seem to have forgotten that (you’d think by now they’d realize that things in their lives aren’t always what they seem). Rumpel himself is equating “undoing” with “death”, though, but I think his undoing may be the result of a precaution he took against Peter Pan.
After Rumpel struck out on his own to find Henry, one of the first things he did was cut his shadow off his body so Peter Pan wouldn’t be able to control him (he tends to attack people through their shadows). He then gave his Dark One dagger to his shadow with the instructions to hide it somewhere Pan wouldn’t find it–to hide it so well that Rumpel himself wouldn’t be able to find it. How does this tie in with my theory? Well, just because the dagger is hidden from both Pan and Rumpelstiltskin, there’s no guarantee that Henry won’t stumble upon it. Once he has the dagger, he’ll be able to control Rumpel, and this could mean that he’ll order his grandfather to relinquish his dark abilities. Rumpelstiltskin is undone as the Dark One, but he himself is still alive. Granted, to him losing his powers would be a fate worse than death, but he would finally be able to patch things up with his son Neal, who never quite forgave him for becoming the Dark One.