Yes. These primordial SMBHs can have masses comparable to entire galaxies. You most likely won't find that much matter collected densely enough anywhere in the modern universe, or ever again.

"ever again".. until the universe collapses in upon itself? (Is that still a plausible theory as to the fate of the universe?)

Current theory is it expands forever until nothing has a chance of ever interacting with anything else.

If you believe Roger Penrose, at that point spacetime ceases to exist since all matter has thinned out to nothing, all black holes have evaporated. Then, because of math I don't understand, a conformal rescaling happens and you get a new Big Bang.

> Then, because of math I don't understand, a conformal rescaling happens and you get a new Big Bang.

I don't think he has any math to back this up. In his theory, it just… happens.