How does black holes die?

 Vacuum in space is filled with virtual particles, little effervescent pairs of particles that pop into and out of existence, stealing some energy from the vacuum to exist for the briefest of moment, only to collide with each other and return to nothingness.

Every once in while, a pair of these particles pops into existence near an event horizon, with one partner falling in and the other free to escape.

Doing the work to separate a virtual particle pair and promote one of them into normal status, the black hole gives up some of it's own mass . Subtly, slowly, over the eons, black holes dissolve.