Why go in that direction? Why not _add_ subsidies to the rail side?
Some of that is difficult: the airlines (worldwide!) benefit from military spending to Boeing; there's no such way to make trainset producers more viable. But I think Branson is on to something (as is Lufthansa, in Germany) by combining the rail and air networks. If your business plan is "get people from A to B" it would be great to see more effort on the rail side where appropriate.
I say: split up Amtrak into islands of short-distance corridors run by the airlines, and license the long-distance routes to Disney: it's already a vacation activity, why not make it one that has better entertainment?
/jordan