What If Kim Jong-Il's Successor Isn't Ready? The North Korean leader's 27-year-old son is next in line, but the military might not support him. Kim Jong-Il probably knew he didn't have much time left when, 15 months ago, he held the first "Worker's Party Conference" -- a gathering of North Korea's political and military leaders -- in 30 years. There, he established his successor: Kim Jong-Un, his heavy-set, Swiss-educated, and reportedly not very bright son, then 26 years old. Sure enough, North Korean state media, almost immediately after it announced Kim Jong-Il's death, declared Kim Jong-Un as the new leader.