This is kind of a hard question to answer because we have so many races in World of Warcraft but it’s fairly safe to say that Legion deals a lot with Elven history, there’s an entire zone dedicated to Tauren lore, Stormheim is a fairly strong piece of Vrykul story… and so I got to thinking.
Source: What WoW race would you like to see featured next? | Blizzard Watch
For me, it would be either the forsaken (undead) or the trolls. Some important things have happened in recent lore that affect them, so a treatment of that would be interesting. Also, undead and troll dungeons are fun!