Getting back to your original point (my apologies, when something catches my interest I can be a little obsessive):

I can see Catra meeting her downfall the same way Hordak did - getting old, and a younger, more cunning, and more ambitious version of herself essentially pulling the rug away from under her feet.

The funny thing is Hordak didn't really seem to mind -- until he found out his "partner in crime" had betrayed him in about the worst possible way. He was perfectly happy to let his second-in-command basically run the operation, and he welcomed her ideas. It's one of his funniest traits: he actually seems to respect people who challenge his authority as long as they have the skills to back it up. That's how Entrapta got his attention, too. No, she didn't fight him, but she simply was NOT

Catra, though....