Blizzard hasn't cheaped out on us like that yet, and I don't expect them to. However, I can see them doing something during an expansion that reflects on those areas. I mean, on PTR Thrall was in Nagrand doing his shammy training; so we're already seeing Cataclysm related additions to older expansions.

considering outland is in chunks, i would call that a cataclysm

i belive they will follow the cata model, redo the outland and add new zones (may be legion worlds) for the next expansion and northrend and new zones (may be emmerald dream) for the following one.

Well, I'm hoping the next expac will be focused on Outland, and will feature these awesome options:

1. Outland races (ethereal, two-legged naga, sporelings, and arakkoa).
2. Total world building, so that Outland is the size of Azeroth, leading to:
3. The ability to go from level 1 to endgame in Outland alone.

In your heart, you know it's right.

@Hob

outland sucks

This is actually what I've been speculating on since they announced Cataclysm. The game so far has gone:
Old World 60
Outland 70
Northrend 80
Revamp Old World 85
Since it's been stated that Outland is just the largest shard of the broken Draenor, I figured they'd do another Outland expansion. And I think it's been said that the final expansion will deal with finally fighting Sargeras. (no proof to back that up, but it makes sense, right?) So that just leaves one more. So my thought is the rest of the expansions will look like this:
Revamp Outland 90
Revamp Northrend 95
Argus (or whatevs) 100
Now that they've said that they want to do it, this is beginning to look like a pretty decent prediction.

While I'm hoping they don't cheese out and make Outland cataclysm I am hoping 1 of 2 things 1) to reach the new expansion zone they place the portal in outland. since it would be an interstellar hub as well a good way to boost Outland traffic . 2) make northrend the source of the legion invasion as well as the access point to the legion homeworld for the same reasons