I wouldn't be surprised to learn [eyeroll] that President Trump knows nothing about the history of North and South Korea, or the "six party" talks. All of the nations living within nuclear-bomb striking distance of Pyongyang have a stake in the outcome of diplomatic talks with North Korea and that they should be a party to the talks. South Korea's capital city, Seoul, is the city that would be incinerated if the North Korean regime ever made good on its threats. So this "go it alone" talk is not helpful or respectful.
Not that I have any ideas or solutions, nor can I predict what will happen. Perhaps the Kim regime can only be toppled by force. Perhaps Kim Jong-Un's own generals, alarmed by his Caligula-like behavior, will deal with him themselves. But I'm old enough to remember when his father, Kim Jong-Il, came to power, and back then, the experts were asking if the regime could possibly survive. The misery continues, year after year. Some more random thoughts: