I'd offer Kurzweil's (I believe?) observation that the futurist predictions that come true are those that substantially improve peoples' needs.
Even substantially expanded rail will never solve the problem of "I want to get from point A to point B, as quickly as possible, whenever I'm ready to leave" in a fundamentally different way. The transit to the starting station might be shorter, and the transit from the ending station will be shorter, but it's still the same experience.
Autonomous cars solve that in the same way an personal automobile currently does, albeit removing the inconvenience of actually driving.
The former is like-in-kind. The latter is fundamentally-different. Consequently, if I am a consumer, how much would I be willing to pay for the former vs the latter?
Cell phones became ubiquitous because they were a fundamentally-different communication experience ("Call a person instead of a location"). Transit will be the same way, if it changes.