Originally Posted by
Katchii
They're not just Demon Hunters, they're Illidari, which means they were created and trained by Illidan. Given the fact that Illidan hasn't been around for a long time and has been busy fighting the Legion since his return and the latest data mining shows that he'll be gone for the foreseeable future at the conclusion of the final battle here there will be no new Illidari Demon Hunters.
The only lore option would be to RetCon how shit went down at the Black Temple during the training of the Illidari and say that people of all races (or whatever races they decide to unlock) were also trained. That said, the Illidan novel is canon and where the lore for Demon Hunters is established and in that book it makes specific mention of Demon Hunters being only Blood and Night Elves.
I understand the desire to have additional races be Demon Hunters, but lore wise it just doesn't fit, so I'm personally against it as I'm a lore junkie. That said, Blizzard has never been above changing lore to fit and/ or create better game play options so...../shrug. We'll see I guess.