I'm not a self-declared expert on N. Korea. What I DO know is that it is and has been a Chinese protectorate for a millenium. China will not allow N. Korea to do anything to jeopardize China's personal interests. China would not like to see warfare on it's border here any more than in the Western provinces where the Uighurs are Muslim and the US/UK/Israel intel services have been encouraging radical interpetation of Islam as well as weapon smuggling.
Not sure about Kim's son. Korea, in my imagery, is one of those places the sun never quite shines on. Whomever fills his shoes has a lot of work to do. Sure, there will be posturing and I"m certain it provides the West an opportunity as well so it's worth watching closely.