What do you think is a fair compromise between player expectations and the reality of Visage Form with a 2022 release? Personally, I don't think all playable races is realistic (though I'd like to be wrong), so this thread isn't about what we think they should be but what would be a fair start for the expansion?
As for me, I think both models of Human, Orc and High Elf is a good start for Visage Form. Male high elf and female human are already covered, so they only have male human, female high elf and both orc models. I don't know about anyone else, but I think Orcs have enough of an association with dragons at this point in the lore, even though they are from an alien world. Dragons were not natural to Draenor, however the Netherwing Dragonflight was formed from black dragon eggs brought by Deathwing (AKA Neltharion, the creators of the Dracthyr). They were altered by nether energies from when the world was torn apart. The Netherwing dragons were born in Outland so if you think about it, a species of dragon is indigenous to Draenor, or the pieces of it at least. The Dragonmaw's culture is heavily influenced by dragons (duh). The origin of the Orcs also goes back to the Titans so you could make the claim that justifies the genetic hybridization of Orcs and Dragonkin.
Evokers likely often use their Visage Form for strategic reasons, such as blending in with a crowd. If you look at it from this perspective, they may choose a form to take based on their needs at the time. That's why I think ultimately speaking, they should be able to shapeshift into a much wider selection of mortal races. If the Visage Form is a magic power, why would it be dependent on the Dracthyr's biological association to the form they take?
Dragonmaw Dracthyr... 'nuff said.