Do you think the reason Blizz won't release High Elves is because they aren't a copyrightable property?
We've seen this problem happen to Games Workshop with their generically named properties having to be renamed to copyrightable names. Such as Eldar becoming "Aeldari", Dark Eldar becoming "Drukhari". Even their High Elves becoming "Idoneth Deepkin" and Dark Elves becoming "Sisters of Khaine".
It seems to me that Blizz calling their High Elves "Void Elves" is the same sort of problem solving... Just a thought.