I was just thinking that a generation gap might be in order. Children do not always agree with their elders. Why not develop a few dissident groups who oppose libertarianism, and claim a right to determine a new future for Atlantis as their birthright. You could have a number of differing groups which would be a constant pain in the libertarian neck. Maybe even some terrorists/guerrillas. It would be interesting to play with various tactics and see how libertarian societies deal with them.