Indeed I guess the crucial bit was 'may well'I don't think North Korea will do that. Sure they posture, but NK is a gangster state who has only developed nuclear weapons to safeguard the Kim dynasty and the ruling elite.
Without them they would be in greater danger of being toppled by an invasion of the south or foreign intervention.
Demographics don't make sense either, they can't occupy a country of 50 million when their own population is half that size. Not in the modern world.