While Supertrains which are truly SUPER would be great, I think there's a bit too much focus on top speed. If you can get average speeds on routes to be reliably around 90-100 miles that's pretty damn good. Faster would be better, of course, but 100 mph average still makes rail and awesome option for many routes.
...adding, the issue is that in many places marginal improvements of existing infrastructure (track repairs, additional tracks on existing right-of-ways, electrification of non-electrified routes, etc.) can do a lot to get rid of the bottlenecks and congestion/competition with freight rail which limits achievable average seed. Real high speed rail will require all new infrastructure, essentially. That isn't to say I'm against the latter, but to the extent that a decent financial commitment to rail infrastructure can greatly improve service quality on existing infrastructure it's worth pursuing too.
