You can add Splash Mountain, Roger Rabbit's Toontown Spin, Tower of Terror, and Mr. Toad's Wild Ride to that list.
The more I think about this, the more I like it. Beastly Kingdom would have just been another castles-n-dragons-n-unicorns type situation that we've seen at lots of theme parks.
Going the Avatar route allows the imagineers to mix 2 things they're good at, sci-fi architecture (Tomorrowland, Star Tours, Epcot) with large, dinosaur-shaped animatronics (Universe of Energy, Countdown to Extinction, Journey to the Center of the Earth, etc.)
This should play right to their strengths.