We will still have two portals to two versions of this city as well as a toy that let's us hearth there. It is only 'gone' in the lore, and they're exactly right. If we can't lose anything or anyone, we're not really doing anything. We need to lose cities, we need major lore characters to die, we need to lose battles. There's no sense of urgency or threat if we magically win everything all the time. Teldrassil was one sided and almost changed the modern game. You go to the zone, it's a smoking husk. The only 'zone' that Dalaran is gone is the one we've never been to before.
