Today we posted a rundown on PAX East information. and one of the pieces of information was that Diablo III's transmog system is not coming to World of Warcraft. This made me sad, of course. Today, Ion "Watcher" Hazzikostas tweeted the following update on that.
@perculia Not in 6.0. We do have major plans to make transmog more elegant as a collection game in the future, though.- Watcher (@WatcherDev) April 14, 2014