That's why I think we'll just stick with simulations rather than explore, terraform or colonise - at least for several billion years.
No Man's Sky is perhaps one of the first iterations, demonstrating what procedural generation can do. Eventually, using quantum computers, which can simulate quantum systems directly given a wave function, suitable Hamiltonian and boundary conditions(*), we might be able to generate a vast number of possible universes with alternate Earths and lifeforms - both sapient and non-sapient. Perhaps there will even be a way to dwell on and explore these worlds by downloading into avatars. When the Sun's white dwarf phase cools to a black dwarf, we might have to move on although the simulations could run slower in real time as less energy became available. The passage of time inside a simulation would not be affected.
* The Wheeler-DeWitt equation suggests this is possible although the implementation is far beyond our current capabilities.
The Wave Function of The Universe George-Flinn-Dissertation.pdf (imperial.ac.uk)