A Demon Hunter without demonic abilities is basically a rogue with some hunter mixed in. Heh, they wouldn't even get +damage versus demons because such things just causes issues in raids.
Pssht.
Demon Hunter as a class has been a popular speculation forever. For a Sargeras-themed expansion, yeah that's the only miniscule chance there is. But since they lack a niche, and pretty much all their iconic spells are used by other classes, it's very unlikely to happen.
"But Death Knights took Death Coil back from Warlocks!"
Ugh