Is it really the end? *Spoilers*

[Iscah]

Yes, but again, we would not need as many crystals as dead ancients. They created him, not just summon him, so the aetherial requirement should be greatly reduced.

That isn't how summoning works, at least by our current understanding. Each time a primal is summoned, it is created anew by the summoners based on their concept of the entity they are summoning.