One thing I did want to point out, is that there will not be any World of Warcraft 2.
To develop a World of Warcraft 2 would be suicide for Blizzard, so instead they're upgrading World of Warcraft to become World of Warcraft 2.
Over the past few years now we've seen the original experience of WoW changed entirely. All of the zones were updated, many older dungeons have been upgraded and will continue to be upgraded over the coming few years. Eventually the Vanilla World of Warcraft that we knew will have been entirely replaced with a new, sleeker model.
World of Warcraft 2 is nothing more then the current model, and going back and improving the older experiences to bring them in-line with current expectations. The list of improvements over the years has been insane, from the Fire & Water to Boss Mechanics and Environments.