I think it would be cool if they did something that was relevant to the current expansion but took place in older zones so we had more of a reason to go back.
I always like those pre-patch invasion type events where you go to older zones to defend against the new big bad. The one for DF was kinda lame.
Would be great if there was more variety/more purpose/way more activities to do for something like that. Imagine if there were non-combat activities similar to the soup event in Azure Span but in older parts of the game. It would do wonders for world building, I think. Or imagine Siege type events but of all kinds, all over the game.
Unfortunately what I am imagining is not WoW. It’s something more similar to GW2. I think it’s too late for a revamp of that magnitude.