Like said, this is really nothing new. We have had zones like this since BC, when they added Quel'Danas and didn't allow us to fly around the island. WOTLK didn't really have a full zone but didn't allow Wintergrasp to be flyable during fights. Cataclysm had Molten Front and Tol Barad without flying, since one was heavy pvp focused and the other had inventive questing mechanics that wouldn't work with flying (like the platforming up to the firehawk roost). Thunder Isle is supposed to be like these zones, minus a big pvp quasi-battleground like TB/WG, and instead focusing on the conflict in a world pvp form with the blood elves and kirin tor.