Talanji in her quest dialogue says that Vol'jin's defiance against Zul impressed her when she was a little girl. That was during Cataclysm, in-universe four years ago.How old is Talanji now, exactly? I don't know what's the age of adulthood for trolls, but I doubt it's high if she grew up from "little girl" to adult in four years. Unless she's not adult yet.
This is a travesty to justify Vol'jin being killed off. As I continuously state, we learn several means to bring fallen trolls back to life throughout our levelling, and those means should've been used immediatelly after Vol'jin's death. After all, Darkspear never die. The worst possible outcome for dear ol' Vol'jin has become a fact.
For those who keep mentioning Bolvar, you're forgetting about your privileged perspective. Only Tirion Fordring knew Bolvar's true fate, and that secret died with him. For the world to know about Bolvar being the Lich King relies purely on the Death Knights, who agreed to serve him in Legion for his aid in return. You'd think of all the people who know the consequences of death, the fear, the Death Knights would want to keep the new Lich King a secret. If it got out, the Death Knights would be hunted down and destroyed for fear of serving another evil Lich King.Edit: Even though I LOVE the idea of Bwonsamdi serving Bolvar, it's just very unlikely.