Their meeting will come to nothing because it has already served its purpose: for Kim Jong-un in showing his people and the world that he is now a force to be taken seriously enough that the US president pays him attention; for Trump in showing that he is a US president who can achieve what previous US presidents couldn't. Arguably if anyone has overinvested in this however, it's Trump. What he does not realise is that Obama and previous US presidents refused to meet with NK because they knew damn well they would just end up being Kim Jong-Il/Un's propaganda piece, giving him credibility in the eyes of the world and back home while being set up to fail (thus undermining their own credibility). But Trump is skilled in abdicating failure and blame, so he'll wriggle out of this. And it's not as if he has any credibility with the world left; his home crowd is what matters. And they will give him the thumbs up.