Sorry, but I think you are relying too much on your rear-view mirror when forming your vision of what you think future generations will be "enthusiastic" about, and do not adequately consider how current and emerging technological changes, changing economic and environmental conditions, changing demographics, and changing lifestyle preferences of younger generations may render irrelevant many, if not most, of your assumptions and expectations about the feasibility and desirability of extending increasingly archaic 20th century concepts of "mass transportation" further into the 21st century.  

This is also why I think the "powers that be" should be identifying and analyzing a wider and longer-term range of current and emerging social, tech, enviro, econ, and political threats and opportunities, while also consulting more with Millennial and younger generations, before making huge public investments in the future those generations, rather than their elders, will actually live in.