This could be really, really disruptive. Build it big enough to move cars, and it kills not only trains and civilian flight, it kills the intercity highway. There is no longer any point to having them, as driving aboard a shuttle is so much faster. It also makes city centers closer to each other (in terms of travel time) than they are to their own exurbs. That is going to be stupidly huge, culturally.

Other predictions: Musk is seeing this as solar powered. Yhea, no. It's electric, its going to run of whatever mix the local grid runs on.

Musk is not going to be the mover behind construction. Most likely first mover: Governments. China, Japan, Europe.. (hey, this could seriously put an end to this bloody crisis!)

Lower confidence: Someone is going to try to make a version of this that crosses ocean. If that works out, civil avionics and shipping are done. Stick a fork in them.