This is just a hunch, but they may use the trolley barn, the Gag Factory and even the nearby interactive stuff for this ride, as well as some backstage areas. What exactly is back there anyway? It can't be so important that it's unmovable, can it?
My guess is that they will retain the neighborhood area somehow while Roger Rabbit will unfortunately be nixed. I say "unfortunate" because it's a great ride, but on the other hand, it is based on a property that is relatively past its prime, so I would imagine that's what they would go after. And let's be honest, would they really use the expansion pad for anything other than Star Wars?
Like I said, however, this is just a hunch.