Originally Posted by
Khrux
The difference here is that an interview at Blizzcon with Steve Danuser (Lead Narrative Designer for WoW) who confirmed the following:
1. The covenants are made up of dead Azerothians who take on a new form in the Shadowlands based on where they are assigned in the afterlife.
2. If those beings returned to Azeroth they'd return to the form they had in life, ie. a dead human goes Kyrian and becomes blue, if they were given a 2nd chance they'd be a regular human again. Not a blue guy.
3. Only the lesser beings in the Shadowlands are native to the zones, the examples given were the Owl creatures in Kyrian and the little "treasure goblin" dudes in Revendreth. These are the "caretakers" of each covenant and help the souls of the dead find a purpose. The Blue Humans, Fae Goat people, Vampires etc. are dead Azerothians that only look that way in the afterlife. They are not a "race" of people.
4. Only us players and notable NPCs who cross over with us, retain our Azeroth forms because we're not actually dead. So our souls don't take a new form and purpose.
Now can all of the above change over time? Of course
But whether you deem it "week old lore" or not, its still the facts we have now. They are stating the story of Shadowlands doesn't support allied races, which makes sense when we're not at war, we're not in an arms race to recruit more soldiers and the people we'll meet in Shadowlands are dead and cannot cross back to the living world (and if they did they'd be back to their original form and not retain their afterlife appearance)
So TLDR; unless they do a complete flip flop on the story they are setting up now. There is no "races" from the covenants that can be playable characters outside of Shadowlands.