Or if there ever is a "big crunch" where all black holes crunch together to a critical mass, would there be another big bang and time then run backwards?
The hypothesis I have encountered is that time would reverse when the expansion of the universe peaked and started to collapse back in on itself. The next big bang would start another run of our universe. I'm guessing the randomness in quantum fluctuations would allow this next run to evolve somewhat differently from the one we are experiencing.
