Demining is a more significant act than releasing some prisoners, because both sides are making themselves more open to invasion from the other. It shows that trust has grown.
I believe that Trump meeting personally with Kim was significant because it showed respect, rather than just sending threats or a flunkie. DPRK is very conscious of its place on the world stage, I mean that's a good part of the reason it has nuclear weapons in the first place: DPRK wants to be taken seriously. Having your head of state meet theirs is taking them seriously.
Trump is a clown. But being able to give credit where credit is due is part of a productive political process, while painting this or that guy as someone wholly without sin or wholly without merit is simply more of the polarised nonsense that has done the US so much harm.
I'm willing to take a chance on Trump's approach to North Korea and China as previous administrations didn't work out. I'm not an expert to say it works but I think Trump deserves some credit as tension has decreased dramatically. Especially given liberal media's portrayal of president and the current climate, I think liberal mainstream media is quite unfair and neocons also unfair. Trump is a unique character which is good and bad.
The whole Khashoggi affair, I do wonder, it isn't mentioned in media, but Trump's moves may have factored in North Korea's thinking. Of course, Obama overlooked rights abuses and crises out of strategic partnerships and overlooked abuses too, but less bluntly. I do wonder if Trump's handling of Saudi Khashoggi was also a message to Kim Jong Un, that the US can be a partner. North Korea has seen US in Iraq and Libya, now Iran, and is convinced nukes are necessary. Seeing Trump handle Khashoggi, similar to how North Korea would behave, may open the door to North Korea a little and dampen their concerns on their human rights abuses. Morally, it's reprehensible but you have to see the big picture of overall peace and improvement of human condition in North Korea. It may be a stretch but North Korea is playing China and US off each other and there's a miniscule chance North Korea could be flipped towards US more.
I've heard Kim Jong Un despises China for being used as a puppet. Also, northern China was part of Korea in ancient times and he sees that as ancestral Korean land. Xi Jinping also dislikes Kim Jong Un for destabilizing and pushing ROK/Japan closer to America orbit. Kim Jong Un hates China for trading and enriching his enemy, South Korea. The abandonnment of strict Communism has also left him stranded and he's forced to usher some reform in North Korea. Kim Jong Un also hates South Korea, even if harmless because its very existence threatens his rule, a shining light contrast to North's terror, darkness, and despair.
All I know is, North Korea cannot continue as it has been for another 100 years as the rest of the world moves forward. I just wonder if Kim will get overthrown by his own people if food security is met. By making sure his people are poor and starving, they cannot challenge his rule as they're too focused on finding their next meal. And reward those who keep others in line, like military and police. Brutal but effective way to keep your people in line. That and Kim's personal habits aren't gonna help him live longer. And his child will have to rule too, just babies, so maybe another 25 years at least before kids can take power? I don't know...but US will prob outlast North Korea assuming we don't destroy ourselves.