The gods are upset on how the humans have run the world. So they decided it was time for a change and humans would be de-evolved and a different species would rule.
The species that would now rule would change into antro versions of themselves, but would have the same brain (except for knowledge of speak and language) so the gods can watch how they run the world.
The humans would be de-evoled into the species choosen to take over. If cats were chosen to rule, the humans would turn into human-cats (more cat then human, four legs, tails, almost everything except hair, face, and skin)
Which species is chosen by the gods.