I don't think a world revamp is actually needed but it makes a whole lot of sense in terms of lore and story. After all the cosmic stuff we're getting back to Azeroth, time has passed and things have obviously changed. Phasing tech is just working well so the new Kalimdor/EK can easily be a new phase of the world.
I am just of the idea that since Azeroth is so crucial in the whole Warcraft universe, we don't really need to go through dimensions to fight bad guys - people will just come at us over and over to seize control of our planet.