cosmology is an interesting subject, and what you're describing is a cyclic model of cosmology like is typical in hinduistic literature. however, physics points in a different direction, indicating that the universe is in fact continuously expanding, which is a non-reversible process.

the exact long-term fate of the universe is not 100% guaranteed. surely "heat death" is a possibility, but renewable energy exists on cosmological scales, so an intelligent species could utilize this possibility to build energy-harvesting machines that keep civilization running indefinitely.