Donald Trump Kim Jong-un

The fact that President Trump and North Korean leader Kim Jong-un have engaged in talks this morning means this meeting will already be deemed a success. All they have to do now is walk away saying they have agreed in principle to some relatively low-level matters and leave the details to their officials. 

Much of the content of the meeting will have already been addressed in preliminary discussions between US and North Korean representatives. So long as the two leaders can stay on script, the process should proceed without problem.