Stop the otherwise disaster
As said before, the Lich King would die. Blizzard made Kaelthas, Illidan, etc, to die, and The Chronicles of Spellborn Gold is no exception. But this does not necessarily mean there would be lack of a king. Someone would inherit the crown and become the new king. Without the direct of a leader, the Scourge would kill all living things on Azeroth for control of the land. Fortunately, someone would take the place as a leader and stop the otherwise disaster. He would be Bolvar Fordragon, probably.
