Well I said in other threads that two tone hair color will work for void elves. Black with blue. White with blue, white with silver etc, etc in those pictures further up. Im ok with the sparkly… thing on the hair, gives a look stars in the hair like stars in space. Farstrider tattoos but slightly different since they are following a new path (Hey, you blood elves got Farstriders and void elves got Darkstriders. Could be cool if they glow differently in the dark) for hair well either new long hairstyles (especially for male void elves) or blood elf hairstyles that is slightly different since females void elves already do have blood elf hairstyles but looks slightly different (and some of the void elf male hairstyles shared with the female void elves I do believe that those that play female void elves wants short hair styles like the male have and that shaved onesided long hair styles just like the female blood elves gotten some male blood elf hairstyles). And the tentacles should be a toggle option. And then the bracers in the hair is so Draenai, should have an option to use cloth as ribbions and to choose color like Draenai can choose color on their bracers on the tentacles and tail and hair.
Now the medusa hair is not ok, or spikey hair or N-zoth eyes (My opinion atleast) since it got nothing to do with void elves as Ion said (void elves are just another flavor of High elves) so in other words…a compromise ( Sure smaller glowing tentacles in the hair look cool but bigger tentacles don’t match for void elves, that belongs with draenai or are blizzard saying draenai were created from the void, by void lords to be slaves to void lords and then to be rescued by the naaru and they help the draenai to build a society and draenai culture 
). If one wants that then they should ask for faceless allied race or k’thir allied race. Void elves were an accident, should not exist…but they “do” and are different than old gods and void lords and there for a threat to the void lords (Blizzard idea was that void elves would just be Thalassian elves with blue/purple skin and Blue/purple glowing eyes, in truth blizzard did not think it through with the void elves. In their eyes it was just new and cool). If they get all that then all shadow priests should be able to have that customization’s as well since they been practicing with void powers far longer than void elves. and as steve dunuser pointed out that the void is just another magical power. meaning anyone can use its powers. The void elves were just blood elves playing with void powers for years (Yes everyone has heard that a million times but some do forget) without changing their physical form at all. And as Ion said at the blizzcon they are just a elite squad, so no more than 20 then if they still are elite. So to continue to exist they need the high elves and the exiled (well “Self” exiled really since they know they can’t go home to silvermoon with this new knowledge since Grand Magister Rommath has banned the practice of void powers, yet they still have shadow priests among the blood elves again blizzard did not think it through with the void elves) blood elves to boost their ranks. which means as I said shadow priest still have their original form regardless how much they infuse themselves with the void they still look like High/blood elves (or human, orc, dwarf, troll etc etc) that just use void powers. However In a different thread I have given suggestion on how they can make more void elves like Umbric and his followers a more safe way. Finding a machine that created that box that transformed Umbric and his followers in a place similar to telogrus rift and bring that back to telogrus rift and use that machine to make more High/blood elves to void elves but safer and where Umbric and his follower are in control and not some crazy Ethereal Nether-Prince.
However if blizzard wants the void elves to be the future of alliance high elves, then sure but the void elves still needs to be “fixed” as a race with better heritage armor (can still keep the void wings but as a cloak so it can fit to any armor) and “real” tabard that has a symbol that unify the Void/Blood/High elves. And both armor and tabard has a blue, a purple and a silver version like the mag’har armor. . I mean this would have been easy for blizzard to made the void elves “better” and more of a true “Race” then a “squad” that switch side. But since the void elves were a last minute decision, they just became a mess really and feels weird/wrong to be with the alliance. And Alleria should be the one that fully leads the void elves due to her experience from second war and the 1000 year war with the legion and Vereesa, Umbric and Auric Sunchaser as her lieutenants.
Blizzard can still change their minds about the void elves, since we seen in n’zoth’s mind that there is a possibility that the void elves can go completely insane, but we do have a working titan forge that can purge void corruption. And I quess we will see what happends to Sylvanas in the new raid 9.1.
Edit: Unless you meant the medusa hairstyle would be like/similar to female void elf hairstyle number 3 awoken but with more tentecals. But Im sure you meant was it to be shaved head and with just several tentecals.
).