The Void Elves need a story first.
At this point I would be extremely open to a complete and total revamp of it. For starters, let’s divorce them from Quel’Thalas entirely. As in, no, Lor’themar didn’t go and exile even more of his people. As it is, Blood Elf Shadow Priests are extremely iffy. That’s wrong.
Go back to the drawing board. Have Alleria borrow the Silver Covenant for a weekend trip to Outland to look for some of her lost rangers out there. We can spring the void trap with the Ethereal guy again, transform the Silver Covenant, and then Alleria’s rangers emerge. They’ve already been through this, it turns out. They’re already Void Elves. Have been for several thousand years, because time works weirdly in the Twisting Nether.
How did they avoid succumbing to the whispers? Meditation techniques. Just go full Vulcan with them. Meditation to calm the mind and body, and then as each whisper comes, analyze it, consider what is or isn’t logical, and determine the proper course of action which is, 99.9% of the time, to ignore it.
These Void Elves have an actual society, a population, infrastructure, ceremonies and rituals and rites based on their new existence. While certain trappings of their past lives act as a foundation, much of what they are now is virtually unrecognizable from what they were long ago.
There is no Magistry, but rather another group of casters whom focus on blending void and other powers together (namely the arcane). Their leader is a mentalist who rivals Professor Xavier in terms of mind manipulation, can even cause a room of people to freeze in place, and then resume, unaware there had ever been a pause.
There are no Farstriders/Rangers, but a group of hunters whom stalk the currents and eddies of the void’s energies, scouting out threats and eliminating them, or bringing them to the aforementioned not-magistry to have their minds wiped of all knowledge of the Void Elves.
Rather than a bunch of tents on rocks, give them an actual city just floating through the Void. Doesn’t have to be too big, really. Half the size of Dalaran would be more than enough I’d imagine. Floating islands acting as home to research, with specimens of void-related entities or artifacts for study.
While it’s far too much work to completely revamp all of BFA to include and develop the Void Elves more, I think a good compromise is simply placing some void-assets onto those islands. We could see one with a lake wherein those mind squids from Naz’jatar are being studied, with Naga void tomes nearby. We could see another were assets from the invasions of the Vale of Eternal Blossoms and Uldum are kept. We could see specimens from Uldir.
These actual Void Elves whom have existed for thousands of years are very divorced from Azeroth, feeling no reason to return to it. The Silver Covenant elves are the ones bringing stuff back and still struggling to maintain their place on Azeroth, led by Magister Umbric whom previously had a different name, but changed it after his transformation. The antics of the Silver Covenant elves are somewhat embarrassing to these long-term Void Elves, but what can you expect from these people whom haven’t mastered their minds and disciplined their emotions?
If needed, have a scene where Talthressar returns to Azeroth with a small delegation of these Void Elves, crosses paths with Lor’themar, maybe even walk in the lands of Quel’Thalas again, just to show how much they do not care about it anymore.
Halduron: “I’m sure this must be painful, old friend, but this is what the Scourge did to the village of your birth.”
Talthressar: “It was simply a place I once dwelled, Halduron. It’s destruction means nothing.”
Lor’themar: “Aren’t you even a little dismayed to see our fair lands in such a state?”
Talthressar: “What purposes would that serve? Would tears and tantrums undo the harm done? Quel’Thalas fell, the southern woods blighted beyond recognition. It is unfortunate, then but we exist in an uncaring and unfortunate universe.”
Halduron: “But… this is Quel’Thalas…”
Talthressar: “Yes, I suppose it is. Just one more kingdom to feel the wrath of war, and certainly not to be the last.”