That would create a united Korea in the same position as Germany after the curtainwent down, spending a huge amount of it's GDP rebuilding half the country from nothing.
They wouldn't be nearly in the same position as Germany was after the reunification. The DDR can't be compared to NK at all. The DDR had quite a few problems but they were not even close to the problems NK has. As a starter nobody starved to death in the DDR.