Could you please illustrate this? A power struggle implies there is actually a struggle, not just the duke taking a gigantic penis to the face with no option for retribution. What options can a duke pursue to fight against something like this.
What if the scenario Silverfire mentioned were to come true and the duke was left with one region. What could he about it?
Lords should be able to check a little box stating they don't want to be dukes, imo, as they can check about not wanting to be marshals.