I agree, but unfortunately it’s unlikely to happen because doing that will require heavy duty surgery because the corner of Ghostlands where Deatholme is located actually occupies the same space as Stratholme in the main EK map.
Additionally, Silvermoon would practically need to be rebuilt from scratch because it leans heavily on the pre-flying “façade” method of city building (as was used for pre-cata Stormwind and Org) and falls apart if viewed from the air.
Combine those two and integrating Eversong and Ghostlands into EK becomes a surprisingly large project.
Yeah, the questing in those zones is almost perfect as it is and I don’t have much faith that the new quests would do the old ones justice. Leveling a character there currently is quite serene since it lacks “modernities” like talking heads and doesn’t try to drip feed you quests like new zones do.