Like I said earlier, I don’t think we need a whole land for Avatar. A single ride in Tomorrowland would be ideal, as long as the show building isn’t overly imposing.
With Avatar in Florida the land is a big part of the appeal, so frankly I want the land as much as the ride, and will have to disagree with you on this. I'd also much rather lose the Hollywood Backlot than any part of Tomorrowland for this, especially since it can be easily winked at as a movie set from Hollywood Blvd and stay within the theming (at least no worse than Monsters Inc. stays within the Backlot theming).