China relies on rail, and a lot of high speed rail, to move their massive and increasingly mobile population. We no longer need to speculate on whether high speed passenger rail can substitute for a lot of air travel.

"...let the market figure it out" would work in a market that isn't already so strongly shaped by subsidies, regulations, and nationalist protectionism.

Autonomous vehicles will have a very large and currently underestimated impact on all kinds of other modes of transportation, but there is a wide range of expert views on when that will happen.