I’d say NK more so than Iran because Kim has got his nukes. If he doesn’t make that count for something real instead of just pissing people off, he’s done, as you say. Iran, on the other hand, has a lot more time to play “chicken” because they supposedly don’t have a nuke yet and Iran has dogs in several more fights than the NK does. In other words, Iran is on a bigger stage with more actors than the NK has.
They have been developing weapons together for decades. It is safe to assume some sort of mutual planning goes along with that. If Iran was ever to act, or NK, what better time could they possibly have other than simultaneous?