[Medox]

Then again, "infinitely" might not even be necessary (got carried away there).

Maybe our full universe fits predictably in some pre-allocated space of such an advanced machine/project and 1 million years on our part is a days worth of disk space on their side. An then there are retention periods too...

Regarding the "substitute for God" part... good point, but what if we really come up ourselves with such simulations? It doesn't mean we are gods (literally), it doesn't even mean we are ourselves in a simulation. Just that we found clever ways to simulate the process into replicating something that we judge as correct (ironically). Like a game nowadays but a trillion times more complex. Looking at how much AI improved recently, what is to say that 100 years from now we cannot simulate this and then cheat our future with data extracted from other civilizations, rinse and repeat, to evolve exponentially.