It seems that things are constantly changing, but to my understanding this is how it will play out:
Phase 1 would include a new dry theme park about the size of Magic Kingdom, a few (2 or 3) hotels and another CityWalk type area. Instead of a parking garage, the belief is that there will be a large surface lot for day guests.
Phase 2 would likely include additional hotels (1 or 2) as well as another water park.
Phase 3 would be another dry theme park built where the proposed surface lot will be built.
Somebody please correct me if I'm wrong. I don't want to confuse people or start spreading false information.