The New York Times editorialized today about the need for the federal government to continue subsidizing Amtrak:

For some time, the Bush administration has pushed for Amtrak reforms, which almost everybody supports in principle. But the administration’s most recent proposal is more like a death sentence – a slow dismantling of Amtrak into regional services while costs currently paid by the federal government would be forced onto cash-starved states. The fatal flaw in the administration’s thinking is the idea that the railroad should be self-sufficient. That’s impractical and unnecessary, given the benefits it provides in taking cars off congested highways and offering an alternative to air service in the post-9/11 era.

Sorry, this is a bit hard to say but the bushies may be right on this one. There is no good reason for “cash-starved” states to pick up the tab for anything either. The various government entities do not need to be in the theme park business.
If Amtrak really does an effective job of getting cars off crowded highways and is a meaningful alternative to the airlines (which I doubt) then for those routes where this is true it should be able to be self sustaining.