User blog comment:The Milkman/Random Rambling: Another Assassin/@comment-1080767-20120920230319/@comment-66716-20120921061540

Even if you destroy them, Cicero and Babette survive. They could rebuild the Brotherhood at some point. By the time he's an adult, the Dragonborn could be dead due to old age or having died in battle, so they could then need a new leader.