^Well, the monobloc/'cosmic egg" idea is a few decades out of date. Have you been reading old Asimov F&SF essays? I can't find any current online references to the term "monobloc" in connection with cosmology outside of a few works of fiction and discussion threads. It tends to be called a singularity these days in formal usage. And there are a lot of different hypotheses about what the nature of that singularity was, including the idea that it was simply a localized burst of expansion within a pre-existing vacuum, a universe born out of an earlier universe. The Big Bang may have been a change of state in the vacuum much like this end-of-the-universe state change that's being proposed.