Currently there is no room for a FP return line at Peter Pan.
I imagine they were looking for a high demand ride with room to add a FP return line. Matterhorn is a natural since they have 2 lines already. If MaxPass takes off, I have no doubt we'll see it added to a bunch more rides. I did hear a rumor they are considering a makeover of Fantasyland after SWL opens, so I wouldn't be shocked if that's when they made some big changes there to accommodate FP. I wonder how everyone would feel about it if they closed Mr. Toad to make room for a Peter Pan FP line........

(purely conjecture on my part, but I imagine it will involve some tough choices like this).