Cities have been looking for the silver bullet solution to transportation requirements for decades (if not centuries). The reality is, that the best transportation systems are an interconnected blend of transportation modes. Using trains from outlining areas to city centers (high volume cars with low frequency). Subways or light rail to move people between high density centers (medium volume cars with higher frequency). Cable cars, trollies, gondolas for point to point needs (low volume cars with high frequency but limited destinations). Busses to service low volume or remote areas (scalable to fit the requiremnts).
As WDW has grown, the demands on the current transportation system has increased exponentially. An ever increasing bus fleet adds to the the road congestion. It only makes sense that RCID look for new ways to move guests around the resort. Pick the correct type of system to move guests within resort areas, between resort ares, from "outlying areas", and to the parks. Systems that can handle surges (park closing) and changes in flow (conventions, runDisney, or new attractions). No one system will prove the solution, but properly coordinating an integrated system of monorail, skyway, light rail, trams, and boats supplemented with (not centered around) busses and reducing car traffic through the major arteries is the key to long term planning and growth. Now that I think of it, kind of sounds like designing the transportation system for an Experimental Prototype Community of Tomorrow!?!