The WDW monorail and bus system seemed to work great when I was kid (and the resort only had a handful of hotels....), but now I feel like I'm being herded on a cattle truck whenever I use Disney transportation. I agree with Robert that it's actually more pleasant to drive between the parks than to depend on the buses.
It will be interesting to see how WDW handles this in the future. In a way it's sort of representative of Florida itself....big and sprawling with questionable transportation infrastructure and no concept of walkability.
It brings Las Vegas to mind. When I visited I was so amazed by how large all of the casino/resorts were, yet they were so easy to maneuver between when you wanted. The MGM Grand is "caddy corner" to the Excalibur, New York New York, and Tropicana. A monorail connects them to Caesars, Ballys, Bellagio, Paris, and Planet Hollywood...all an easy walk to one another. And it makes sense for Vegas because, let's face it, most people go there for activities after which driving is a terrible idea.
I too like Universal Orlando and Disneyland Resort, though I would be willing to bet that if Disney could start from scratch they wouldn't put the entrance to California Adventure directly across from Disneyland again. I believe the facing entrances is one of the major problems in getting the public to view California Adventure as a truly separate theme park. I think the distance or you could say inconvenience of park hopping in WDW works to Disney's advantage. No one calls parks like Animal Kingdom or Hollywood Studios, which to this day are severely short of attractions, just an extension of Magic Kingdom like they do California Adventure.
Getting back to the topic though the transportation system at Walt Disney World (bus network) would be a "real mass-transit system" by most definitions. What are you expecting Robert? Walking paths through the woods, a train system or an underground subway network?
Disney in my opinion has made it pretty clear that they don't intend to expand the monorail system or link any additional resorts. It doesn't make financial sense to so and it isn't an efficient transportation model. The monorail is cool, but the cool factor is way overridden by the fact that it has a single point of failure. Even if Disney were to link additional resorts they would still need a bus or other transportation system to serve as a backup. That makes the monorail proposition very expensive.
I firmly believe that Disney really likes their bus network for its redundancy. If one bus fails it inconveniences a few, but there is another bus that can be quickly dispatched to replace the one that is out of commission. It also scales to demand. During busier weeks additional buses can be put on the road, during slower weeks fewer need to be used.
Unfortunately, I don't think the lessons learned from the Super Bowl really apply to the theme park world. They certainly apply to city development, but not so much for theme parks as I doubt we will see many parks, especially theme park resorts built in the US in the next decade or two.
The trains would result in fewer vehicle, substituting electricity for diesel, reduced workforce over the hundreds of busses, reduced bus accident risk, and more opportunities to market to the guests. I would expect a reasonable payback period.
A hub point get tremendous traffic with potential to be highly profitable. Ease of access to the hotels could make the hotels their own profitable mini-attractions.
Right now it is the cost of fuel, bus repair, bus union and accidents versus a brand new monorail fleet and monorail lines and a new matainence building. The current monorails are too old to go on for another ten years, so about 20 new monorails would be required. The cost to build a beam has come down since the 1980's.
Combining the Magic Kingdom express with the EPCOT line makes almost no sense. Cycling trains through EPCOT when it closes at 9:00 pm and Magic Kingdom closes at 1:00 am would be a wasted effort. I figure the station changes (Ticket & Transportation) center could be done with minimal changes to the existing since a stop going to and coming from Magic Kingdom at this spot would still be necessary, but sending every train on to EPCOT doesn't make sense.
Now combining the MK resort line with EPCOT, kind of would make sense.