My "one thing" is actually two things that others have mentioned:
1) Forced mortality once your character has reached a certain age. Keep things the way they currently are, until yor character hits, say, 60. Then they become mortal like a hero. And as they get older and older, the chance to die from wounds gets higher. Eventually, *everyone* should die of old age. Start at 80 or so, and have a small, but growing, chance of dying from old age once every RL month. No more immortal characters who will never, ever have any chance of dying.
2) Start the one-noble-per-island rule on every continent. Don't force-deport anyone, just make it so that if you already have an active noble on an island, you can't start or unpause another. Events over time (deportation, death, retirement, pausing, etc.) will, over time, thin the herd. (Yes, this will mean that if you pause both of your characters, you will only be able to unpause one of them.) Combine this with #1 above, and you will sooner than later get to a situation where everyone has one noble per island.