The revolts will just try and wreck the place, not capture it and set up their own tribe.
In the Noble update, though, disloyal Nobles could split off and form their own tribe.
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My current thinking is that each Noble will belong to a House, with 3 Houses generated at the start of the game. When there's a revolt an entire House will rebel to form it's own tribe. That's not set in stone, however, I do like the idea of individual Noble's splintering off.
Nobles wont get uppity due to not enough alcohol (though with the Revolts in the Morale Update your citizenry might), they'll be more concerned about politics and influence.