I would see stronger benefit to negotiating with China rather than North Korea. If Trump could entice China with economic deals and build an overall stronger relationship with them, there will be no need for North Korea. China will stop massive trade with North Korea and essentially fracture the entire country. The need to have them as a buffer zone will be eradicated and China will be able to rid their hands of them. Even Xi Jinping hates Kim Jon Un and wants out of this alliance badly.