It would be foolhardy to think that anything disney puts out right now is a "Done Deal"
They guard their pennies now...and many of their releases are more for short term PR rather than a long term construction plan.
Universal did very well in a horrible travel economy last year with Harry Potter and Disney knew it. I'm not saying disney HAS to respond...because they are the big dog and they aren't in danger of losing their hold on the market...
But to the PR department...an announcement of something that can loosely be called "bigger" would have value to them as a counter tool. They can push it with travel agents and roll out marketing overtime to say "hey...we aren't running worn out parks into the ground...we still got it"
But that is really PR.
Because they signed a creative partnership with lightstorm...that is far from a guarantee of new capital additions in the parks. Creative partnerships are signed/ renewed all the time and often the ideas generated are shelved or bagged altogether.
The disney/ lucas deal is a good example. Granted we got star tours and some indy coasters....but beyond that there have probably been hundreds of ideas proposed that might have had support but were canned for any number of reasons.
This thing with Cameron could be the same...they have an agreement and a plan...but we know that Disney is not the "push through...damn the money, full speed ahead!" operation anymore.
Heck, they couldnt even go ahead and put in new cars/speakers on space mountain last year that were put in
disneyland in 1999.
All plans are flexible because of accounting...the new reality of disney. (and by "new"...since the takeover in 1984)
The other thing that universal did that was a "gamble" by disney standards is that they rushed forward to get the harry potter area up and running when the material was still fresh.
Disney NEVER does this...they refuse to just get the thing built/ running. And i believe it is because of two reasons:
1. its cheaper for them...bigger gaps, delays, and earlier announcements takes the heat of them to do more reinvestment and construction...which obviously they are focused on moving forward
2. Giftshops...they waited years after even their most successful franchises...toy story and nemo...before they build attractions based on. That's because its about the showdump, not the show. Guaranteed revenue is all that matters.