Slightly different but related thought: what if inside of each black hole singularity is another universe? The stuff it collects ends up in this other universe. Which would mean our universe is just "inside" the black hole of another.
Then perhaps the accelerating expansion of spacetime we detect here has something to do with the accelerating accumulation of mass of our "parent" black hole.
That would add an interesting spin upon multiverses. Without a doubt, black holes and understanding them are very much key to many unanswered and unknown questions.
to me it's more rational to think that each black hole is just punching a hole in our 4-d spacetime fabric just like a sharp point can punch through a bag. what the stuff drains into - I have no idea. Perhaps a higher-dimensional space that contains our universe?
Then perhaps the accelerating expansion of spacetime we detect here has something to do with the accelerating accumulation of mass of our "parent" black hole.