The Warchief of the Horde has been missing, while the war against the Burning Legion is at heat. The wording of the quest text (Dalaran) does not imply he is dead, although it must not be ruled out as a possibility.
Where could Vol'jin be? He played a catalytic role in overthrowing Garrosh and he succeeded him as Warchief. In Warlords, he only visited the player's garrison a few times. Moreover, we don't know if Vol'jin took part in the assault on the Broken Isles or not. It is highly unlikely that Vol'jin is dead, he hasn't been Warchief for long and he hasn't had the chance to prove himself as the leader of the Horde. Probably, Vol'jin is on an undercover mission and will emerge when the time is right. The most popular theory is that he is going to unite the Troll tribes for the fight against the Burning Legion.
Sylvanas Windrunner is the new Warchief in action
This is probably the most interesting piece of information merely because it arises a huge number of implications and hypotheses. The Dark Lady was more than eager to replace the missing Vol'jin and lead the Horde to the Broken Isles.
Sylvanas is one of the most popular characters in World of Warcraft and her story is deep and complex. One would expect that the defeat of the Lich King would bring her relief, but it only seemed to have hardened her resolve and made her more cruel. Her distaste towards Vol'jin becoming the new Warchief was apparent, while there is a mutual enmity between her and both Lor'Themar and Baine - which makes us wonder how and why she was chosen to become the Warchief in the first place. Nobody knows what is in her agenda. Is the Banshee Queen on the track to become a villain?
