Just an observation, and I know it's better to suspend reality for this thread, but the yellow area houses some of the most important maintenance buildings in the park. There's a lot of heavy industrial machinery (some custom built for Disneyland) that probably couldn't be moved to another location without some serious ingenuity.
I love the ideas though! Mine would be to turn the Fantasyland Theater/Big Thunder Ranch area into an "Indiana Jones" themed land. Perhaps even putting "The Temple of Peril" somewhere there.