. . . "This sort of quid pro quo is exactly what the US is looking for. The only reason the US would invade the North is if Kim were to threaten us or the South Koreans with nuclear weapons. But he can't threaten us with nukes if he doesn't have any. In short, the US gives up relatively little while Kim gives up nearly everything.
That's why we should be skeptical of this offer. At this time, it's impossible to discern Kim's endgame. There must be some confidence building measures carried out by Kim before the US would commit to such a course of action. If those steps are taken, we can be reasonably sure that Kim is sincere about giving up his nukes.
But Kim is nothing if not complicated. Can it really be this simple? A man with zero credibility has just offered to disarm. Caution is still called for until Kim proves with his deeds that he can be trusted.