It seems pretty obvious to me that some variant on the vacuum maglev train is the long-term solution to travel on Earth. It's the only way, really, to get past the air problem. I doubt we'll ever see mass supersonic transport - a far riskier and more inefficient game of fluid dynamics russian roulette.

It's not going to happen overnight, though. We're waiting on a few technological breakthroughs before it becomes viable. Fully automated robotic tunnelling and construction, for one. Automated manufacturing of those robots. Much improved materials science, probably nanotech-enabled. But when these technologies come, it's inevitable that we build such a network.

The time isn't right for vactrains but it will be eventually. The future is here, it's just not evenly distributed - and this particular future has been creeping forward for literally centuries. Give it a few more decades and we'll see the real hyperloop!