So, let's assume there is a system that keeps a few hundred people firmly in power and they treat/view everyone else like cattle. What would they be most afraid of?

Some of the cattle becoming aware that the "elites" exist? No, that's easily dealt with by lawfare or worse.

A supposed "maverick" coming into political power? Nah, they have stacks of kompromat and a real outsider would never make it that far anyway.

What they really fear is for the cattle to rally around a common identity and organize in numbers they cannot handle. That's why they constantly attack Whites and Men, because that is where the danger lies.