Even lengthening existing Amtrak trains can take years of time and bureaucratic approval. The design of the Acela trainsets is such that Amtrak could add four more business class cars, which would double the number of business class seats per trainset, while keeping the current power cars.
Transportation improvements over time tend to make some trips possible in much less time than was previously possible; this is true of the automobile, the Interstate highway system, the jet airplane, and the Golden Gate Bridge. Nobody has demonstrated a 150 MPH bus running on the existing Interstate highway network yet. High speed rail has the potential to increase the distance that can be covered in a 60-90 minute commute.
Boston, NYC, Philly, and Washington DC could all be commutable with existing technology. It'll probably take 25 years before we decide to build it. This went live in 2004:
http://en.wikipedia.org/wiki/Shanghai_Maglev_Train
Transportation improvements over time tend to make some trips possible in much less time than was previously possible; this is true of the automobile, the Interstate highway system, the jet airplane, and the Golden Gate Bridge. Nobody has demonstrated a 150 MPH bus running on the existing Interstate highway network yet. High speed rail has the potential to increase the distance that can be covered in a 60-90 minute commute.