My feeling is that widespread high speed rail will never take off in America there are too many barriers. Two that come to mind that will delay and increase the cost to prohibitive levels are Private Land acquisition and Environmental assessments and preservation laws.

What I think will be a more realistic "High speed Rail" option for the US is using existing infrastructure in new ways. Something like fully automated cars, where each car is similar to a rail car and the connection between cars is digital not physical.