I'm agreeing with the consensus here. An Avatar attraction, while misguidedly cashing in on a fad that people have already moved on from, wouldn't be a terrible thing. It could be a fun attraction, and in ten years when absolutely no one cares about Avatar anymore they could re-theme it. Easy as that. However, and entire Avatar Land is a bad idea, for all the reasons listed above (non-Disney properties should not get an entire land, replacing fad land will be a lot harder than replacing fad attraction, weird sexual themes, heavy handed environmental themes, and themes of genocide don't really go hand in hand with Disney Parks, etc.), but also one more big one:
It will be an enormous waste of space think Dinoland Part 2, and you'll be getting there. The problem I have seen with Lands based on a single property is that there's not enough ideas to spread around to multiple story driven attractions. Think about the lands at Disneyland. You typically have one big E-Ticket attraction surrounded by other smaller rides, and shows that all tell unique interesting stories that you can't experience anywhere else. Now think of A Bug's Land: It's Tough to Be a Bug surrounded by dressed up kiddie rides. Cars Land: Radiator Springs Racers surrounded by dressed up kiddie rides. Toy Story Playland (Disneyland Paris): Dressed up kiddie rides (they don't even bother with an E or D-Ticket here). Wizarding World of Harry Potter: Harry Potter and the Forbidden Journey surrounded by two run of the mill roller coasters. See the trend?
Yes, in all of these cases the theming is really cool and is part of the draw. Recreating Radiator Springs is awesome, as is visiting Hogwarts Castle, however, the actual attractions are typically lacking. Real, classic, Disney Lands have a good combination, great theming with several great rides, not just one and filler. That is what we'll get with Avatar Land. We'll have one cool (probably 3D, because that's the *only* reason Avatar was so successful) attraction, some interesting theming and filler. Ooh boy, I can't wait [/sarcasm]. If Disney really wanted to do something with Avatar it would have been much better to incorporate the E-ticket attraction into a land with a broader idea that lends itself to more unique possibilities. You could even theme the area surrounding it in close proximity like Pandora. An Avatar attraction as part of a re-imagined Beastly Kingdom (obviously re-imagined to include sci-fi creatures) could have worked really well. An Avatar Land, is going to be a massive waste of space and awkwardly clash with the rest of Animal Kingdom.