At the correct carbon price, which would only be about 10% more for flights, you could just take whatever transport was cheapest and that's it. Job done, planet saved.
The trains and boats and planes would compete to offer faster, cheaper transport. Some people would choose to do other things.
It's systemic change we need, not individuals re-arranging their travel plans on what they vaguely feel is a better way.
Most of the changes are utterly boring, like apparently cargo ships can save money and carbon by going 10% slower.
Business cases for little plane sized hydrofoil boats will open up:
https://www.youtube.com/watch?v=RT26zF6Y2Bs
Or e-methanol powered ships or whatever. It doesn't really matter what the eventual solution is, what matters is that we start pricing in the externalities.
Luckily, we as a global society are actually doing this, and having far more impact than any individual ever could, but we could have done this faster and cheaper, and we still could accelerate it if we understand this.
On the particular topic of transatlantic flights, regional air mobility looks likely to be a thing, so this same plan could work just with electric planes at either end rather than/as well as trains. And carbon taxes would probably push us in that direction.