Somehow I don't think North Korea will die the way East Germany did.  East Germany was one of the most successful COMECON countries, whereas North Korea has been one of the least successful.  East Germany also did not whip up hatred for the rest of the world, especially their capitalist sister, the way North Korea has.  

I don't think South Korea or any other democratic country will have the balls to invade North Korea.  But I do think that there is a possibility of China invading North Korea.  It wouldn't be a full-scale war: it would just be an adjustment by the Chinese of the North Korean government.  The Chinese would replace the Kim Jongs with a puppet government more aligned to the Chicom style.  The Chinese would offer to pay to help feed and rebuild North Korea, in exchange for rights to military bases in North Korean territory.  Who knows, they might even absorb North Korea as a semi-autonomous state of Communist China, kind of like a Soviet republic type thing.  The thing is that China wants to prevent North Korea from being absorbed by the South far more than the South wants to take North Korea back.