Domination of worlds by alliances and players who have already defeated the fortress.

I say that Once an alliance has beaten the fortress it should be made to break up and not stay in the same alliance, also, no more than two "old" alliance members can be in same alliance.. You call this "punishing" them, I call it creating new challenges.
Instead of sitting around like fat frogs on a log snapping up the little flies, they are pitted against one another to further refine who is the best.
Send them evenly to the 10 corners of the world to make new friends and Conquer anew!