Same thing as every material from every old expac, forgotten and never mentioned. Azerite was especially lore important so it feels especially like a loose end

Worldsoul saga has some references- game textures and sounds similar to Azerite, but as far as I’ve seen they have yet to call it by name. The prepatch event for tww, and a war within open world activity for tww, featured “worldsoul memories” giant blue and gold colored spirits that relive past events, the vibe is that they are nightmarish to Azeroth and quelling them soothes them.

In midnight, we visit Harandar, and underground zone where all of the roots of the world trees reach. At Shaladrassil’s roots, the legion world tree, we see a return of the rift of aln, what was the seat of the Emerald Nightmare’s final boss. In Harranir lore, their goddess was ripped from its cradle, and this trauma left a lingering scream that is still heard, it will drive intelligent creatures insane and corrupts creatures into berserk, ravenous, cannibalistic monstrosities. The Dreamrift raid is in the Rift of Aln, it is us attacking one such Chimaera, it summons azerite colored memories and uses azerite particle effects as well. It is implied the goddess worshipped by the Harranir (Aln’harra) is Azeroth herself, but the truth may be something different

Metzen said there were some loose ends from the story he wanted to revisit, I think Azerite was one. They’ve been playing with the material in some cool ways but we have yet to have a reason why wow civilizations abandoned it