he’s still young as hell for a leader. He will probably be in power for a few more decades for him to have adult successors.Looks like he's going to be the last of his line as a dictator in North Korea. If he dies "suddenly" there is no way there giving power to the kid.
Unless he gets assassinated in a coup which at that point it doesn’t matter whether he has legitimate heirs or not too. They’re getting killed as well.