She won't be killed off.
She will, either, end up like Azshara:
Queen Azshara says: Now go and do what you will. I tire of intermediaries and heralds. The true throne of power beckons, and I intend to claim it.
Azshara opens a Void portal behind her and disappears through it.
Or, like Illidan:
"As he dies, however, Illidan reminds her that 'the huntress is nothing without the hunt'."
"After Sargeras is defeated, Illidan takes control of his body and kills Gul'dan the same way Gul'dan killed Varian Wrynn, ripping him apart with fel energy until only his skull remains."
Blizzard seems to hint at that with the latest cinematic, showing her displaying some humanity:
https://m.youtube.com/watch?v=MPOvUQIbP9s
Her role, after the Shadowlands, would be to train a new generation of Dark Rangers, and by doing so - introducing the Dark Ranger as part of the playable classes of WoW.