There is one aspect of the North Korea talks that needs to be brought up.
While the US congress is asking for consultation on any deal President Trump makes the real question is going to be on the North Korean side.
One of the problems with running a death camp the size of a small state is the even as a dictator or a family of dictators you can’t do it alone. There is a large infrastructure involved of people from the guards who actually beat, murder and rape those you wish to oppress, to their commanding officers to order and supervise this being done to THEIR commanding officers who make sure these orders are carried out all the way up to Kim.
Even more important is the need for an infrastructure to eliminate anyone who doesn’t carry out said order, or who would rebel. You might think for example that Kim had a bunch of bodyguards because of external threats but I suspect it was the job of a lot of those guards to keep an eye on each other.
And that the real danger here.
All the way down the line from the very top general to the guard at the gulags are people who make their living or get their kicks and power from the Kim regime. The moment that North Korea beings to open up and do things differently a potential threat arises to that power.
If they can be convinced that the gravy train will continue unabated then there will be very little to worry about
But If enough of those people decide that any nuclear concessions are a threat to that continued power they might decide they would be better off with a different member of the Kim clan in charge and if they find a member of said clan who agrees and is willing to go along with a purge to make sure that their stranglehold on the country continues then all bets are off.
Of course this scenario also depends on them avoiding raising the suspicion of all those people watching them whose job it is to purge any person thinking of launching a purge but don’t think for one minute that this dynamic isn’t going on and don’t think for one second that the Chinese would not use this method to exercise their veto if they find they don’t like where Kim and Trump are going long term.