A revamp would be great, but I do hope that the questing of Eversong and Ghostlands doesn’t get “modernized” too much in the process. Some cleanup is ok, but I really enjoy leveling new alts there because of how “zen” the experience is, with the lack of pop-up talking heads, vehicles, voiced lines, etc. The more bare bones questing really makes the zones themselves the star.
At the very least, integrating Quel’Thelas into Eastern Kingdoms will require them to move either Stratholme or Deatholme, because they occupy the same space. I have an older post here with more details, including pictures: