Is the question ive been pondering after finishing Rise of the Ynnari, Ghost Warrior.
Spoilers related to the book.
Since Yvraine does not find the last crone sword, nor a clue to its true location. I am starting to wonder if Games Workshop intentionally set her up for a neverending quixotic quest, the elusive goal just of reach and strongly hinted at bringing great upheavals should it ever actually suceed.
A good comparision is the return of Guiliman, which utterly changed warhammer 40k with the return of a living primarch after decades of a teasing possible return when all was lost.
Ynnead is believed to be fated to destroy slaanesh and free the eldar from damnation. Should that happen, it would be a major upheaval in the setting and certainly causing a lot of pouty slaneshi supporters. Would GW dare to go to such a lenght? Looking at Age of Sigmar, where Slaanesh is missing, theres potential for Slaanesh being deleted in 40k too. But I think AoS had an easier time of it, starting with Slaanesh already gone from the beginning, and the horned rat taking its place in the chaotic pantheon.
So unless Slaanesh is slated for removal in 40k too, I have hard to see how the quest of the Ynnari could ever be fulfilled. Unless they have completely misjudged Ynnead and it becomes a far worser monstrosity than Slaanesh, though it seems unlikely. At Yvraine's death, the Yncarne was sorrowful and crying silver tears as it took her into its embrace. It actually cares. The grimdarkers would surely frothe with rage at the thought of a benign god of death, even if it was -seriously- hungry for soulmatter as seen during the Yncarne's rampages through enemies.
But one could wonder, should even a caring Ynnead ever destroy Slaanesh, would it be sucked into the chaotic pantheon to take its place?
What do you folks think?