We have had Cataclysm zones longer than we have had Vanilla zones in Warcraft now. The story in these zones is very outdated and doesn’t really fit into the story of “the world” as it stands. With the current ability to play any expansion fresh out of the box so to speak using Chromie Time, I feel that they should revamp the world, they can keep cataclysm in the game as they can just instance this away now and this won’t impact other people, this is already happening with the current game and works well in places. This will also allow a fresh new perspective to be undertaken. Allow the Allied Races to have buildings around the world and camps/towns. Give Gilneas, Exodar, Silvermoon an update and allow them to be cities people can venture into repaired and rebuilt (as the all are except for Gilneas in Lore)
The absorption of the new Studio will allow blizzard to assign extra devs to assist in rebuilding. It doesn’t need to be a ground up build like Cata was as the foundation is there now, where cata did not have this backbone and needed a full rebuild.
The excuse being thrown around that “shadowlands time flows differently” is the perfect excuse for this to take shape and unless we have another “cataclysmic event” I don’t know how we can expect a revamp as such but using the “time excuse” is they can easily get away with it. They could even install some tech to some zones to have the ability to be replaced in the future for other expansions down the line, ie Zidormi can just phase the single zone like Silithus and blasted lands etc