That this is happening between the Koreas indicates that all parties recognize the abdication of the United States in the peace process. The Left are in control in Korea at the moment, while the Right are in disgrace. South Korea, for its part, became an economic powerhouse through nationalization of industry under military junta; democracy in South Korea dates back to like the late '80s.
Meanwhile the status quo in North Korea is untenable. They're rife for food shocks, much of their export industry (narcotics, counterfeit dollars) has been curtailed through policing and China benefits more from leading reforms than they do from propping up a despotic nation.
Jinpeng has set himself up a cult of personality not seen since Mao. He's playing a long game. North and South Korea negotiating with each other isn't unheard of; Kaesong operated for fourteen years up until Feb 2016. China for its part is a permanent member of the UN security council. If they can get inspectors in where the US couldn't, they achieve a PR coup.
I've slowly developed a perspective on the world under Trump. The US had all these initiatives and projects around the world that we're now allowing to lie fallow. That they were largely unopposed by the rest of the world means that the world, in general, wants these projects to continue. If the US can't keep it up, someone else has to. China can now make a play to be the stabilizing force in Southeast Asia. Russia can make a play for the Middle East.
And we can have a military parade!