I skimmed through a textbook on quantum field theory a while back and found something that stuck in my head. It goes something like this:

Matter and energy are equivalent via E=mc^2. By dimensional analysis we see that the square of the speed of light is a coupling constant that makes matter and energy inseparable, equivalent, different manifestations of the same stuff. This equivalence is demonstrated by experiment, where energy is released by radioactive decay, reducing the mass of a radioactive sample. Even kinetic energy can be converted to mass when particles collide at high velocities.

The energy of a photon is given by the equation E=hv, where h is Planck's constant and has units of J-s, and v is frequency, or alternatively wavelength. Therefore Plank's constant couples energy and space (or time). So energy and spacetime are proportional, different manifestations of the same thing.

A little matter represents alot of energy; a little spacetime also represents alot of energy; so matter can also be equivalent to spacetime. One cannot exist without the other. Where there is one, there is always the other. So if a black hole could theoretically absorb all the matter in the universe, the spacetime it occupied would also be simultaneously absorbed. The host universe would collapse at some point because there would be no matter in it.

But what about temporal dilation? The intense gravity of the black hole might dilate time so much that we would perceive a more gradual effect: the black hole might remain small until almost all the matter in the host universe is absorbed, then an accelerating inflation would occur.

But I'm way out on a limb. Like I said, it's just a neat idea.