I actually would be excited about that one!
Seriously though, and I'm sure it's been mentioned (I haven't read the entire thread) - Avatar was a hit because it had groundbreaking CGI. Not a groundbreaking story or theme. In fact Cameron's story-telling has always been his weakest link. The next one will probably be a blockbuster, but won't be shattering box office records, by any means. For one - it's taken too long to release the sequel, interest has dwindled - and for another - more interesting things are out now.
Disney might as well have bought the rights to Twilight and done a Bella and Edward theme park. It would have created just as much animosity. This is their answer to Harry Potter, but HP will be around for generations. Star Wars (and I'm not a fangirl) would have been a smarter business approach because it's stood the test of time. Avatar has already scored a low grade on that test.