Do black holes last forever?
A. No, black holes evaporate by a process called virtual particle production (see Hawking Radiation). In this process a particle pairs up with it’s antiparticle at the event horizon. Normally particles and antiparticles destroy each other on contact, but in this case the black hole rips the particle and antiparticle apart before they can annihilate each other. One of these particles fly off into space and the other falls into the black hole. Since the one of the black holes particles have just been lost, the black hole has lost mass, and since this is happening all the time black holes are always losing mass.
