A goodwill visit? That sounds more like a cover for talks with China about how to avoid a military conflict. China has no problem engaging in bi-lateral talks with North Korea if it serves the interests of China. My guess would be that these meetings are essentially made up of someone from North Korea pleading with someone from China not to attack, and someone from China demanding they give up their nuclear weapons program. It looks to me as though China's dropping into some shotgun diplomacy.
I have considered that Pyongyang or at least some faction is trying to mediate a way from an impasse. But I only would place more weight on that position if I thought that I saw other signs of bad relations between the "teeth and lips."
However, I am by no means an expert on either Korea or China, and perhaps indeed we will see swift action from China to displace the Kim regime. We live in interesting times.