Here’s the thing; Dalaran inherently “breaks” the world. It exists in two different places simultaneously, which means that the world will ALWAYS have a weird time-break, no matter what. The only way to fix that is to remove one or the other.
Now, here’s the thing; I KNOW this is actually a lot of work. There are quest NPC’s associated with both versions of Dalaran. However, I do have a solution in mind.
See, NORTHREND’S version of Dalaran doesn’t actually have THAT many quests associated with it. The NPC’s that are there, could simply be moved. I would personally build a very simple Kirin Tor settlement , either in Crystalsong Forest or at the end of the “Path of the Titans”, overlooking Crystalsong Forest.
Just move the quest-related NPC’s down to the Kirin Tor settlement, maybe spruce it up just a tiny little bit, and you’re done.
Now, for LEGION’S Dalaran; because there are SO many quests associated there, it would just be wildly impractical to change it. What I might consider doing, though, is maybe it feel a little more grounded in the setting itself, maybe having them “land” it right beneath where it currently hovers.
My reasoning is simple; as fantastical as it might seem, I personally feel like it crosses the line of “immersion” to simply being wildly impractical.
I would also use it as an opportunity to maybe make a couple of SMALL improvements. Maybe Krasus’ Landing is repaired, and all of the Class Hall portals are moved there. When you enter the “center tower” or whatever, that’s where you can move some of the more obscure portals (the ones Legion-Dalaran used to have, and probably Argus as well). I’d probably also restore the Capital-city portals for each Faction.
Also, I might also suggest breaking down the “walls” entirely (except around Violet Hold), since I feel like that could give you a really nice view of the horizon over the water.
Dalaran has always been probably my favorite city, and I imagine a lot of players would echo that sentiment. I’d love to see it given a more permanent home though, and given how deeply it is tied specifically to the Legion expansion, I think that makes sense to have at its new home. Giving it a few little touch-ups along the way, I think it would help with the growing focus on world-building.