It's not a dream technologically, I'm sure we can eventually figure out HOW to do it. It's a dream because no one would ever be willing to spend the amount of money required to actually BUILD it. This is a country that can't find money to make sure it's bridges aren't dangerously corroding. There's no way they're going to spend 10+ BILLION on an experimental train.

Airplanes are going to be around long after we're all dead and buried.