There is no known limit. It is possible that in trillions of years when we don’t exist, there will be a merger of millions of super massive black holes that reaches some physical limit and they “super nova” or make a new “big bang” or something. But logically, the gravity of a black hole is such that no other forces can do anything but comply. As gravity grows stronger it really just becomes gravity and matter-energy that are relevant. All the other forces can bugger off for all a black hole cares. Which is weird since gravity is technically the weakest force of them all.
But, what is the limit to this run-away gravitational phenomenon? It’s unknown.
The Broad Spectrum Life 