It’s hard to imagine that Kim’s successor would be worse. But the fact is very little is known about the handful of regime insiders in the military, intelligence and security establishments who would fill the vacuum left by Kim’s departure. There is no reason to think a replacement would be easier to work with; it could easily be worse, more virulently anti-American, more prone to provocative action and less adept than Kim Jong Un has been so far at dancing on the cliff’s edge. In fact, in most historical cases of regime change, the relationship between the intervening country and the new regime does not improve.