There is one area where I think trains could make an in road to air travel that is in markets where the trip can be done overnight. I was thinking about NY to Chicago, Tucson to LA, and such. If the train was a sleeper which could be boarded early and you wake up in your destination, it might be comparable to the cost of travel and hotel. The rail cars would need to start where people board. Today to take a sleeper from Tucson to LA you are at schedule risk of a train which comes all the way across the country. Looking at the fare, I think you pay for the room to come all the way across the country even though you would only be in it Tucson to LA.
Another problem with rail travel is rental cars. This week I went from Connecticut to Philadelphia and had to take SEPTA to the airport as the rental counter was closed on Saturday. In Connecticut getting a rental car at the rail station seems to be very difficult.
One more idea to get into the mix was mentioned above, that is rail needs to connect to the airports. I could see taking a train to a larger airport as opposed to a short haul aircraft, but today except for Newark and BWI, I think most trains drop you off downtown not at the airport.
