It's possible Kim blows him out just like he did Ibarra. Zapata was less impressive at flyweight, but boy oh boy was he good at 108.
I've said before that Zapata is one of the most talented fighters ever defensively, but this is a pretty poor match up for him IMO. If a similar stylist in Ibarra just gave out under about five minutes of that South Korean pressure, and we know that Zapata is quite gettable early, given that it happened multiple times, I can see Kim getting him early. The other scenario in which I can see Kim winning, is that Zapata's reflexes and ego trick him into thinking his defensive wizardry is winning the fight, but in reality he's admiring his own work too much and being out-hustled. Although I think the most likely scenario is that Zapata comes in like he did vs Penalosa, and schools the shit outta Kim before stopping him.