To be fair, while Umbric's research might have started with Dar'khan, he now has Alleria and, through her, Locus Walker, who are much more reputable people, especially Alleria who is a Ranger-General and hero of Quel'thalas and the Second War. Even despite her exile, there should be people who would follow her. Learn the ways of the Void with Alleria Windrunner! Study the secrets that cowardly Kael'thas-lover Rommath doesn't want you to know! Guest lectures by the Locus Walker, an ancient Ethereal from K'haresh! Learn to protect Azeroth by studying the power of its greatest enemies! Find a way to leave those smelly orcs and detestable undead behind you!
But yeah, it's probably in 100-1000, especially considering that the whole population of Quel'Thalas can probably fit in 100000 range.
No more then 50.
I don’t doubt that more then a half of Silvermoon suddenly decided to delve into void magic and were banished from their homeland. Why not? It’s not like Thalassian elves have been through a severe decrease in population numbers lately.
Oh, sure, civilian population would ignore such things. But I imagine there are plenty of Magisters and other powerful people with opinions who would find that being an enemy of Quel'Thalas wouldn't be that bad, considering that the Void apparently cures the Sunwell dependency. The same kind of people that are likely to have the will to resist the whispers of the Void as well.
13 though blizzard could just turn all the high elves into them and call it a day.
It is clear that Blizzard intends to have the Ren'dorei's numbers grow considerably, otherwise they wouldn't have introduced Sin'dorei and Quel'dorei NPCs in Telogrus, the mysterious seat of power of the Ren'dorei.
Don't you have a broken Fel-infested city to clean up? Get to work.
The Void. A force of infinite hunger. Its whispers have broken the will of dragons... and lured even the titans' own children into madness. Sages and scholars fear the Void. But we understand a truth they do not. That the Void is a power to be harnessed... to be bent by a will strong enough to command it. The Void has shaped us... changed us. But you will become its master. Wield the shadows as a weapon to save our world... and defend the Alliance!
population number has always been an idiotic excuse for not having something playable.
only 12 people are 'canon' in the warcraft lore. the rest are nameless, faceless adventurers that effectively have no race or class. those 12 are the highlord, netherlord, deathlord, archmage, arch druid, shadowblade, huntmaster, grandmaster, highpriest, farseer, slayer, and battlelord.
so there could be a group of elite soldiers with only 12 members, and they would work as a playable race. population size has never been, and will never be, a good argument against a race.
TBH, that's just a username I use because it sounds nice. I always format it as "Arenchac of <Location>" and change it around pretty regularly. I don't actually roleplay in forums that are strictly meta unless you're specifically around for me to remind of the glories of Nexus-King Salhadaar.
Anyway, as I was saying, on a scale of 1-10, how likely are you to pledge yourself to service for the Sacred Ethereum Invasion Fleet, the mighty strong arm of Nexus-King Salhadaar, the most intelligent, powerful and sexually attractive dictator in the Great Dark? And would you rather serve as a meat shield for our infantry, or work the salt mines back on K'Aresh?