Remember those phone calls between Trump and Nieto, and with Turnbull? Here is a link to the transcripts, in case you forgot.
Basically, the phone calls play a bit like this scene from Bad Santa, except that neither Nieto nor Turnbull are ever allowed to ask whether or not Trump is just fucking with them.
What we learned from the Nieto and Turnbull phone calls-- and really, was obvious all along-- is that Trump has no business having high-level discussions with world leaders. I did a longer write-up here, when the transcripts were originally released, but Trump is in over his head.
So, what could go wrong? Realistically, he won't be allowed to sign anything. His handlers won't let him. The worst case scenario is a leaked recording or transcript of Trump being Trump-y. He'll back away from any supposed commitment that would undermine national security, so you don't actually have to worry about that. This is the upshot of Trump having the consistency and political fortitude of jello on everything except his racism, which won't really be an issue here unless he starts doing racist impressions of Asians, and he'd never do that, right? Right?
Fuck. Who made that man a President?
Anyway, that aside, the likely worst case scenario is another Nieto-type moment. Trump acts like Trump because he's Trump. Some documentation gets released, Trump looks like a dipshit, Kim has a good laugh, the rest of the world wonders what the fuck is in our water and whether or not General Ripper was right, and that's it.
For anything beyond that, for an actual policy change, you'd have a lot of people involved besides Donny. Would he do something stupid? Sure, but he can't read, and reading is fundamental. I think I saw that on tv somewhere, but if it ain't on Fox News, it doesn't exist to Donny. There is a distinction between having the wool pulled over his eyes by Kim and imposing tariffs-- simplicity. Any formal agreement between the US and North Korea that involves any complexity involves people other than Donny. Remove him from the decision-making process, and his meeting with Kim becomes nothing more than typical Trumpian spectacle.
Should a president meet with North Korea, without preconditions? The Republican Party's position used to be that meeting with a country was a reward for doing what we want. Now, Trump is President, and he's being Trump-y. The party's position must change for the sake of Trump-defense. Mine doesn't. Trump is unlikely to accomplish anything, but unlikely to do much in the way of policy damage. Mostly, this is just a higher-stakes version of the Nieto and Turnbull calls in that he should expect everything to be leaked, and look like a twit, but he always looks like a twit.