It's a great idea, and we should start working on it today.
Because most of the initial objections to the plan are lame. They could have been--and no doubt were--said for all major transportation systems.
To wit:"The $6 billion cost estimate is not realistic." Yes, the Hyperloop will probably cost many times as much as Musk says it will. If so, it will still be relatively cheap. The new "high speed" train California wants to build is supposed to cost about $70 billion, and that estimate is no doubt absurdly low, too. "Some of the technologies have not yet been fully worked out." Of course they haven't. You could say the same for any ambitious technology project. That's not a reason not to start trying to work them out.