Waving numbers here and there is - sorry, not sorry - STUPID take …
Draenei didn’t came in tens of thousands, but if you’re using properly that what grows on your neck you’d know and you’d see they’re distinct separate race. Thus they became a core Alliance race.
Earthen are constructs of Titans - they’re the original uncorrupted version of all known Dwarves (either be it Dark Iron or Classic Dwarf).
Mechagnomes - same as Earthen!
Both of mentioned above are distinct from their ‘Curse of Flesh’ corrupted versions.
It’s not a number what makes a race, it’s their obvious difference - thus even there would be only 10 Draenei, they’re still a separate race cause they’re different to any other core race in game.
Same principle goes for Void Elves - not big in numbers - but possesed/corrupted/altered by void. Change to the core what makes them distinct from other Blood Elves.
The biggest possibility here is that Void Elves and Blood Elves will get more customization options leaning towards High Elven Culture (same as we get Amani Customization for Darkspear Trolls).
Other possibility (though I am sceptic about it) is to ‘unify’ all Thalassian Elves under one banner and one name - Quel’dorei - making them true neutral race, being able to act with both factions, being able to choose your desired racial ability (either classic arcane torrent or other voidy thingy)
Alliance High Elves = Horde Twilight Hammer Humans
that’s what I see when people are asking for High Elves
Even with 500 new customizations to look like TRUE High Elf, people will still complain about one thing - your name tag will not say high elf and I think for some people this is a huge existential crisis …
Personal wish - stop this nonsense with adding new races every single expansion - rather focus on story development and world evolution (yeah, Hyjal still burns … yeah Ashenvale has still a magmalord floating over a mountain… yeah, there are still Legion ships over Broken Isles … yeah, two warfronts are still active even after war is over)
EDIT: Personally I like we have customizaton for both void or blood elves to look more like original high elves - we can have nice skin tones, blue eyes … but what’s enough for me it’s not enough for others. More customization would be cool, but I wouldn’t go die hard to get high elves as separate race).