Originally Posted by
Biomega
This is almost guaranteed to never happen. It's too expensive.
Cataclysm was kind of an experiment, and it didn't go well. It's great that they revamped old zones and all, but it also spent vast amounts of resources on content many people didn't give a shit about because they weren't going to level new characters, or not level them in those zones. It effectively wasted a lot of expansion budget on something that wasn't actually a big expansion feature onto itself. Even if you DID level a new character, you got to see some of it for a little bit, and then it was done, and it never mattered again. Whereas other expansion features tend to have more longevity - even "seasonal" content like Korthia etc. lasted people a few weeks. Nobody took a few weeks to level a character through all the new zones. Heck even just leveling one character often didn't give you a full zone's worth of story, because you outleveled the zone too quickly and didn't get to see the conclusion.
Art assets, world remodelings, etc. are incredibly labor-intensive work, and therefore expensive. But the payoff just isn't there. So it's not something we're likely to see ever again, at least not on the scale that the original Cataclysm had.