Humanity won’t all die. The vast majority might, and all the rich have to do is make sure they’re among the survivors, in a situation where they’re still on top of the remaining society.
They would need to "noahs ark" enough people with the skills required to keep them rich. And at that point i dont think the remaining slaves would have as hard a time rebelling.
They’ll manage. The most important task in Noah’s arc is loyal security. This has been practiced for centuries if not millennia. If a rebellions is successful it makes it into the history books, such a rare event it is.