So many times i see people without knowledge make false statement.
Zandalari were there almost every time you encounter troll lore. They helped us in vanila during ZG, they came to Northland to recod fall of the Drakari empire. In cata and MoP they acted like enemies (followers of Zul).
https://wow.gamepedia.com/Zandalari_..._the_Lich_King
read this pls before saying that Zandalari have no chance being DK. Only problem with "logical" reason is "why zandalari DK join horde during LK". But since every new zandalari we create are already part of the horde - we know that this DK can actually back to zandalar/stay in northrend and only after BfA joing horde.
it's blizzard fail that they created such race with such STRONG lore. And blizzard aware of it. But trust me - only outrage if blizzard allow zandalari have many classes will be from Aliance, cause "horde love", but TOTALY NO LORE LIMITATIONS.