I do think that if we get new hair colors, it will be when AR get their customization pass. To a degree I believe that VE's need for unique hair textures since they include the tentacle -unlike the skin tones which were reused as is and only required separating the jewelry into a different texture- influenced as to why we didn't get new hair colors now:
Almost everything AR have gotten have been reused assets and splitting of already existing options -no new textures have been made for AR except for eye colors- so even while new hair colors are nominally easy to make, they have to be made on the first place, unlike the BE skin tones that are literally being reused.
So I do think it's highly likely VE's will get new hair colors, when AR are updated -who knows will that be- the only question is if they will try to replicate BE hair colors, or will use the opportunity to keep the difference? That could work either way for the HE fantasy; they could add hair colors that only fit VE aesthetics, or they could add warmer colors (blond, brown, etc) while still making them different shades -perhaps less saturated- than BE counterparts.
Personally, I do think we will, eventually, get more hair colors, maybe even blonde and brown, but will not be the same, because I do think if they wanted to do so, they could have made VE hairstyles use two textures -one for the hair, one for the tentacle, which could have allowed the use of BE hair textures as is, which is the case for skin tones-
So in short, I do think there's a chance VE's will get hair colors that fit the HE aesthetic, but we won't get them now because they need to be made rather than just reused like skin tones were. But I also don't think they will be the exact same colors that BE's have.
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Why would the High Elves loose "claim" to their name because they are a subversive political party? Specially when the majority of their race already changed their name to something else?
It's like saying Pandaren should change their racial name depending on which faction they are.
Like for sure the Alliance High Elves could change their name to something else, just like Blood Elves did, but they don't automatically lose their name because they are a dissident group. And again, since Blood Elves already changed their name, it doesn't even cause confusion, which it shouldn't, since Pandaren have done it since MoP
The question is why people refuse to call Blood Elves... blood elves, which is the name they chose for themselves.