All I can tell you is that in most jurisdictions around the world that is precisely what has happened. Where there is high-speed rail for a relatively short period of time--and I'm talking about three- to four-hour trips, not twelve hour trips--the passengers have shifted to train rather than air for two reasons: one, the convenience; and, two, generally speaking, the rail systems have been able to offer more competitive pricing because they have much higher volumes in the same unit.
On May 14th, 2009. See this statement in context.