8 minute 46 second mark
"When the team was planning Warlords, Grommash was set up as the leader of the Iron Horde and the final boss. As they told the story and started working on Hellfire Citadel, they decided it wouldn't be a satisfying direction to go in. Players had just finished a raid zone full of Orcs and had killed another Hellscream. The real evil and more interesting character is Gul'dan and the influence of the Legion."
So who will it be? Will Gul'dan come back one way or another? Another Legion based character? Or was Archimonde the last boss?