i'd like to propose...
that civ's that make it past the annihilation barrier, would likely try and find equilibrium with their environment, eventually becoming indistinguishable from natural processes. so if we were looking for them, maybe they're already right there but we cant tell the difference between them and nature.
maybe that last cup of water you drank contained some aspects of some highly evolved consciousness.
in which case, shame on you for pissing them out like that!