Futurology

Except the concept is already "proven" in that regard. What the issues are with it, are the same as with everything techy that needs to make it in the world - scaling it up.

It's impossible to hold a vacuum in a tube that's hundreds of kilometers long. It is impossible to build a vacuum tube that doesn't suffer because of thermal expansion. It is impossible to build that long of a tube and it not have a single dent in it across the entire way. Even if you somehow ignore physics, people don't need a train like this. There is flights. Travelling at reasonable speed has been proven for hundreds of years.

To explain it in a tldr way, I can grab a straw, put a wet tissue inside it, blow on it and in relative speeds it would go incredibly fast. Yet nobody would go for trying that with a train, since scaling it is impossible.