Hawking handled several theories in ocations I think that these theories is like saying I am going to say several even if it is one I have to get it right.
By the theory that I understood from wikipedia if a black hole is not devouring a star or planet this usually disappears with time, of course this contradicts a bit the latest study on the theory that a black hole never diminishes.

But it can also be that an active black hole gains mass because it is constantly devouring and that a hole that has nothing nearby to devour loses mass and disappears.

As the saying goes, if I eat well I grow healthy and strong, but if I don't eat anything, I die and disappear.