Blizzard announced several features for the expansion that should make WoW veterans very happy. These features are changes that need to play a long time. They will perhaps enough to get former players resubscribe.
Balancing class players through PvE and PvP in World of Warcraft has been a long struggle for Blizzard. They must ensure that the capacity is useful in dungeons and raids, but not so powerful that it would give the character an unfair advantage in the battlegrounds and arenas. The solution Blizzard in the Legion is to provide a separate PvP talent system. As players earn Honor class, they can unlock special abilities that only work in battlefield and the arena. In addition to the PvP balance easier to achieve, the new system takes the focus on the Honor mill and conquest. Your choice of PvP talents and how you use them will be more important than equipment.
World content specific to the class of Warcraft has always been uneven. In WoW vanilla, Paladins and Warlocks could continue long questlines to get special mounts. Burning Crusade allows druids gain a form of special flight. Many other classes never received such special treatment. legendary weapons, meanwhile, were generally well suited to handle classes but not others. The solution Blizzard in Mists of Pandaria and Warlords of Draenor was to offer rings and coats that each class could use legendary. However, coats and fuzzy rings differences between the characters rather than making each unique feel.