Ok, getting back to the original topic of this thread...
Seems to me that IF the train and RPW are going away for Avatar, it would probably just be the guest portions of RPW that are going away. That is, the actual animal care, etc could remain, with no guest access, except maybe backstage tours. That would allow the land now used for the train and the walkway at the RPW end betewen the train station and the facilities to all be used for Avatarland, along with the plot that is already cleared behind Kali and Maharajah Jungle Trek. The entrance to the land would be along the east-west path between the bird show and Africa. There's plenty of forested area there that could be used for the entrace, leading to what would be a pretty large area between the cleared plot and the land now used for the train.