Speculations over a future reunification of the Koreas have been going on for decades since the War ended and the two Koreas signed the Armistice Agreement in 1953.
Below is the photo I took during my stay in North Korea of the Arch of Reunification, a symbol of the Korean reunification proposals put forth by Kim Il-Sung. The two women symbolize the two Koreas, and together they are holding a map of a unified Korea.
The idea, a pipe dream for now, has met tremendous difficulties in order to even envisage a possibility of reunification. Not only the two countries have grown considerably different both politically and economically, but also continuous tensions between the two nations have this process more unlikely to happen.
Kim originally proposed a federation of two states where initially the powers would remain as they are today with a foreseeable slow transition. However this proposition has met many difficulties as the proposed unification expressed by Kim would follow a German-unification style with the big question on how the South Korean government would handle such a scenario and what should be done to transform the North Korean economy (of which we know almost nothing due to lack of statistical reliable data).
As far as we know, on paper, both Koreas are firmly committed to the principle of national unification. During official contacts between the governments, both sides mention that the unification should peaceful and gradual and that they should be able to co-exist. Hopeful words in theory but still unlikely in real life, although not impossible.