Doug,
I'm not sure I follow the airline part of your post. Perhaps it's a typo you didn't catch. Airlines certainly didn't replace trains in the 1800's. If you want to pick a timeframe when that began to occur in earnest, post WWII would be a more likely time. When jet aircraft went into service in the late 1950's the move away from trains accelerated. However, as we all probably acknowledge, automobiles had a greater effect than the rise of airline travel on the death of the passenger train. I'm not sure where you got the conclusion in the next sentence, but it's not true for pre or post 911. Net-meetings have had a very small effect, possibly not even accurately measurable. The economics of airlines are very complex and are affected by so many other factors, both internal and external that putting it down to one thing is simply not true. Any real discussion of airlines economics probably isn't useful on this board anyway.