You mean turning on their master. In that case, Kim Jung-il's days are truly numbered.
Just the opposite. Kim's doing what he needs to do in order to survive. The cold war is over, and global communism is dead. Forget what you learned before, because the old equation has changed. While the Koreans and Chinese have historical ties, it's hardly one of master and servant.
The new relationship is simply. China wants to be a big power, and every step they take in that direction takes them further away from North Korea.
North Korea wants to survive, and they can't count on the old Communist powers to back them anymore. Nuclear weapons are they only way to scare the world into compliance.