When I say "dark ride" I refer to the original definition which involves UV light and flourescent paint for a night time Pandora world, the ride could be as long as Pirates, and perhaps even have some thrills. Not dark ride in the sense of rides like Peter Pan which are sort and have few thrills.
The thing is that Cameron walked around AK and was dreaming up what Pandora would look like. He wants Disney to spend $500 million+ on a land based on one film, and help promote a non-Disney franchise in the making. He wants enough money to get it "right", and Bob Iger is on a power trip thinking that adding a new successful land to a theme park is as easy as buying up the rights to a blockbuster.
To really make an Avatar-land they would need to build around a half-dozen of those tall trees, it would be like building five Swiss Family robinson tree houses, then they would need to fake massive floating rocks, or add waterfalls and a lot of rock work. Then they would have to put in fiber optics and leds everywhere to make the place look good at night, as well as build fake plants and mix them with real plants. I am guessing this would cost around $400 million to do this, and we haven't even started talking about a ride. This isn't a fake mountain range, but hiring people to put in a lot of fake leaves by hand. A couple rides would add on $200 to $300 million, if you include restaurants. About $700 million, or more, for a land with a couple rides and a restaurant, it could easily cost more than Carsland. Cameron isn't stupid, he knows that it will cost more than $500 million, and Disney wants to scale back the cost to around $350 to $400 million . . .
I had completely forgotten about Avatar's memory tree thingies, guests walking around at night would probably just see light up trees. Avatar is not yet an important franchise like Star Wars, and is more forgettable.