It's not that there aren't enough pax trains. Its that aviation has out performed rail in this country effectively killing it. For those of you who play the market, (or those of us that were avid (like the super nerdy type) model railroaders in their youth) know that that has turned around because of 9/11 and the recent economic downturn.
The issue is, rail travel hasn't put up the technology yet to be competitive with motoring the highways or flying. With the advent of mag lev's we've seen that change, however its important to note that the infrastructure in this country isn't exactly "built for the successes of rail travel" and furthermore, I'm not certain our society is either. By that I mean, people are going to want a train to stop in every little town along the way to "connect" places rather than get from A to B. This is the same problem aviation has faced and frankly, the same problem thats bankrupting it. Sending a DC-9 into grand forks or thief river falls instead of "just fargo" kills them.
The other issue that's been pointed out, securing the rails. Ultimately, this will (to be most effective) need to be buried, or elevated. That or they would need to send a lead train through to ensure clear tracks, or perhaps a warning horn on the tracks (like a claxon or something) but no one would go for that.
All of that said, I think this is simply awesome (if it happens) notice I said if as opposed to when. Literally, growing up in love with trains has shown me that the only thing certain in the rail industry is that it is dead in this country and people don't GAF about it. With the airline industry though treating their customers the way they have for so long, this is likely the only time in recent history that I'd say it stands a chance of being profitable let alone successful (wait switch those).
Lastly... its unfortunate that this rail system will be built by politics instead of engineers or transportation analysts. By that I mean, the reason certain places are getting rail systems is largely political (or at least partly) and that will have unfortunate ramifications for its success. Much like aviation, the only companies making any money in rail transport these days are freighters (check CSX stock) and the fact that AMTRAK is a government run company scares me.