indeed, this is another aspect that actually is better explored with night elves and void elves. Mainly because Nightborne show no strong affinity there, and the ranger side of the blood elves actually has diminished greatly with far greater focuses on the arcane fire magic and blood magic, even the astromancer side picked up in TBC has been largely second place to fire, arcane and blood magics. But then this was largely night elf territory and fits the void elves much better.
Rangers would be something that fits both sentinels and silver covenant farstrider rangers, as well as the Umbral Rangers, given Alleria, the leader is also a ranger as well as a void magic wielder, not turned magic wielder, she is more than one class like most racial leaders and legendary lore heroes are.
I heavily suspect that most of the blood elf Astromancers that didn't join the legion with Kael'thas actually are the ones that became void elves, curious about the void and the stars. I mean it makes sense, and if it wasn't exactly thought of, I would add that piece of information to void elf lore when it is expanded