Chiming in a bit late, but Vashir and Deepholm appeared out of no where.
New Islands show up all the time.
There is still I believe a spot unused on the Eastern Kingdoms map north of Eastern Plaguelands/West of Ghostlands, or there used to be a shaded area that wasn’t clickable.
Traveling from the Worgen town in the past version of the blasted lands to Booty Bay took me past a long stretch of beachfront property on the backside of ZG that was undeveloped.
I also wasn’t specifically saying the horde had to have the new zones, but if one was taken from the Alliance (given to the horde, say Hillsbrad/Southshore) and then replaced by a new zone (say Islands off of Westfall) it would have been a better experience overall. Especially since Southshore was mostly dealing with Naga, Murlocs, and making Turtle Soup for the Alliance. All perfect for an Island zone.
Maybe then Cata wouldn’t have started the bleeding of Subs.