Well... after 40 years of experience in Japan, and after 30 years of experience in Europe,  high velocity trains are a seasoned and dependable technology. They're unbeatable over distances which imply less than three hours of travel time. Which at current commercial speeds means 600 to 700 miles. Whenever the high velocity train arrives, airplane routes doing the same service lose between 40 and 60% of passengers; and it's a distance where railroad is clearly more proficent in energy/passenger/mile than airplane.

It would be great if the USA began implementing this technology in urban corridors like those in East and West coast. It would save energy and pollution and likely would increase productivity as it's far easier and cheaper to implement wireless technology in HVT than on airplane -so the business passenger is able to work with his laptop while he/she travels. And that's not future technology, it's what you get in Europe now...

I'd like to see a nuclear powered train system with a single power plant electrifying a lot of track.
Sure,  ~70% of France's electricity is nuclear, so the TGV is a nuclear train, but bullet trains could be run at the same economies as intercity freight, subways, and cable cars if it's all based on the same dedicated power source. Both the East and West coast corridors of the US could benefit from an integrated nuclear rail.

Nuclear power is expensive, but not so much in comparison to the energy/pollution costs of moving freight. I'd like to see if it would be justified from an economic perspective.

 

Fusion would be better 

Helium is a less troublesome byproduct than radioactive waste, IMHO. Too bad fusion is still not viable as an energy source.