
Originally Posted by
milkmustache
I believe this is the case, but there's plenty of reason to believe that a large portion of the early versions of TWW were repurposed.
I think even looking at the tonal shift from 10.0 to 10.1 and 10.2 (not even counting some of the big question marks like Vakthros) we can see something happened behind scenes to change course on the story beats. Iridikron all be seemed to be the final boss of Dragonflight right up until 10.1.5. It's an interesting idea to consider whether or not Dawn of the Infinites always existed in the way that it is in game (particularly Iridikron's involvement with Galakrond and Xal'atath), or if it was going to be all Infinite. But maybe the bigger question here is about Xal'atath's involvement with Iridikron.
I think that TWW, the Earthen and maybe the Arathi and the Harrornir were a main part of the initial TWW outline along with Anduin's return, Azeroth's calls, and the gambit for the Worldsoul. I think Xal always was, but the general story around it was most likely drastically changed to fit this 3 expansions arc, which is where we get things like the supposed highlight of the Harronir in marketing but their near absence in 11.0 (and Rootlands remaining in the files), etc.
My long ramble summary being: you're right they work 2 expansions ahead (our Dragon Isles reference first came in BFA, death and Shadowlands hints came in Legion, etc.), but I believe Metzen returned around the end of Shadowlands and the stark lane changing of the narrative in Dragonflight that coincided with that leaves a reasonable assumption that TWW went through the same, if not more intensive, narrative changes to fit the new vision of The World Soul Saga.