I am now, have been and will be wrong

 

Until something like this is fully and universally enforced, we'll have the free rider problem.

 

I'm not sure if this will help or hurt air travel to the 'marginal' countries.  But if you can fly to the boarder cheaper, and then take the train, won't that be your itinerary?  What will that mean for those cities?

 

In anycase, someone will figure out the most advantageous approach, and force a different scenario than originally planned.