And boy are they doing it. As we knew, Desolace and Azshara are getting revamped completely, while Feralas is in for some questing changes and zones like Loch Modan are seeing some "light" modification. Blizzard apparently looked at each zone and determined where it lay on the list of todos: Azshara is becoming the 10-20 Horde zone and so will get reworked extensively, but Silithus, while it may need work, probably won't get more than a few tweaks.
Afrasiabi also talks about the surprising origin of phasing and Blizzard's philosophy. More after the break.