Hey it only happens once so you get to chill in the fields or as a monster. And with no people around it means monsters are the new normal and given enough time shining monster civs and cites will dot the landscape. Unless the whale can planar shift to nuke the afterlife and decides to nuke the new monster world in which I believe the phrase "Turtles all the way down" applies.  As monsters get zapped and either escape into monster heaven or get turned into the new fiends which are humans.