In the long run anything is possible, though there are no specific moves in that direction at present. Generally, North Korea has long had a specific policy of reunion with the south, and in the past South Korea was also keen to encourage closer relations through its 'sunshine policy', which aimed to reconcile the two nations through diplomacy rather than military action. However, less has been heard about this in recent times. Last year there were talks about helping to bring families back together which had been separated by the division of Korea; but the talks didn't succeed in the end. The two countries continue to have regular disagreements, which sometimes involve the deployment of the military.
The two Koreas have been divided since 1945, and the majority of people in both countries have never known unification, so as time passes it could become less likely that any leader will find a way to reunite them. However, until even a few weeks before the fall of the Berlin Wall, few people believed that East and West Germany would be reunited either, so you never know.