Whenever I'm reminded of demon hunters, I would go a bit further and predict void elves are more stable. The whole point off Alleria's journey, the quests and the void elf intro, is to show you these guys can actually deal with the whispers in a more permanent way. This is not like the void purged kro'kul Alleria meets, that barely hangs on only to eventually give in, or Cho'gall and his mad cultist that have clearly and willingly given in to the madness. Here I predict blizzard are defining a more permanent thing almost as if to say they can't give in to the whispers, this is what sets the locus walker ethereal apart, there is a certain state or level in void interaction you reach to be classified as able to resist the whispers, Alleria is the first mortal and the void elves are the first race of people to do that.
I would like to see blizzard flesh this out properly either by a deeper explanation or sequence of events that will show void elves will not or even cannot fall to the whispers. The Illidari seem on more of a knife edge, even though those who complete training are able to master the demon within,taking a very skilled deceiver like Kil'jaeden or some extra ordinary circumstance to turn them evil legion style.
The Illidari And now Void elves are proof elves have a high tolerance and affinity to magic that can allow them to handle dangerous stuff like the fel and the void without getting corrupt, it is a boon for them and fitting because we use to think elves were the most easily corrupted or altered by magic. They can be, like we see with the night elves in Azshara, the highborne Naga, satyrs and the nightborne withered state, and also the children of the highborne, (The Thalssians) via the Wretched state, but the opposite is also true, they can also withstand and beat the corruption or madness of some of the most seductive magical powers, like fel and the void. And it is fitting, that if they can get quite corrupted, they can also get quite resilient in a way other races can't .
Remember the night elves are born of magic, they have a special relationship to it that is part of every elven group( since all elves are variations of night elves), yes, even the alliance kaldorei group whom contrary to popular belief, do have a very high magic affinity that is not lost or missing, and again contrary to popular belief, Thalassian elves are only a minor variation of them. For all we laugh at the night elves for the hubris and recklessness that led to the legion, we almost never bear in mind the extraordinary capacity to handle an intense torrent of arcane safely, without destroying themselves or blowing up their empire, they knew how to use magic expertly and were supremely confident in their ability, until that crossed over into over confidence, leading to recklessness and then those who thought themselves beyond corruption had fallen to it, and now this is the only aspect most fans remember or even know of their magical achievements and capability, that is until Illidan Stormrage comes at first and proves you can handle fel without the corruption of your soul and beat the demon within, then Alleria Windrunner comes and shows that the same elves can handle the void too, successfully without giving in, it is the sort of level of skill you expect of an elf,.
What I would like to see is an insanely powerful elven arcane user on the scene. Elisande could have been one, except she is only an echo now - unless they restore her. A great candidate would be Prince Farondis, the elves could do with an arcane champion ... especially after the string of humans (Aegwyn, Medivh, Jaina, Khadgar).
I would also love to see a Thalassian magic champion too, they have one for hunter and Paladin, but none for priest, mage or warlocks. Arthas Sunreaver could be used for mage.
Archangel Azshara/Illidan level - Farondis
Fire mage - Thalassian Blood Elf
Frost Mage - Thalassian Void Elf
Arcane Mage - Shal'dorei Night Elf
Destruction Warlock - Thalassian Blood Elf
Affliction Warlock - Thalassian Void Elf
Demonology Warlock - Shal'dorei Night elf
High Priestess - Tyrande Whisperwind
Discipline Priest - Thalassian Blood Elf
Holy Priest - Kaldorei Night Elf
Shadow Priest - Thalassian Void Elf
Arch Druid - Malfurion Stormrage
Balance Druid - kal'dorei Night Elf
Resto Druid - Kaldorei Night Elf