It has been so long now I can't put my finger on how long ago Avatarland was first announced and still so far off in the distance. I had that same feeling about Fanasyland Expansion. I was in Circus shortly after it opened and remember being most impressed by how pretty the colors of Dumbo was and the peanuts in the sidewalk but for the most part that section was just a remodel.
Don't fret too much yet. Maybe after the family trip is complete and a few months have passed he might have a change of heart for his kid-less trip. Mixing the expenses of both in his head just might be too much in his head at the moment. 
