I find a monorail/light rail or people mover system the most likely options. Are cable car systems like the Hogwarts Express capable of (multiple) turns beyond about 45° with a reasonable radius? I can only think of fairly straight line installations (yes, I know HE has the jog in its path, thus the "fairly straight line" part). Plus, what DH said seems like this was before reclaiming the south resort parcels, which I think makes a cable car system even less likely. I'd look for some kind of light rail/people mover/PRT system.
I would imagine they are going for something similar to the LinQ in Las Vegas...it is zippy and doesn't take a ton of time to get around..perhaps with the HE concept thrown in..but that would take away from the actual HE attraction's magic I think