The shutdown accelerated this, but it's far from the root cause. Even when it lifts, it's still on a bad trajectory.

Can't reduce training standards without causing lots of other problems.

Automation in older ways is possible but complicated. More modern AI would be a disaster. Though they might try.

There isn't really an answer. Air travel can't continue as it was, and there aren't enough plans for trains to come close to making up for it.