I was always thinking it would be a flashback quest, either for a cinematic or – possibly more likely, given the scale of it – something akin to the Huln quests in Stormheim. I wonder why it would be scrapped though, and what it could've been used for that would necessitate it being made in 8.2. Perhaps it was for a previous incarnation of the Ysera storyline for 9.0 that would've involved a flashback quest?