That seems like a pretty optimistic estimate, but I suppose its a guessing game for such a hypothetical system anyways. Also, for comparison BART ridership tops up at over 100 million a year[1], and 6 million fly between LA and SanFran annually[2].

[1] http://www.bart.gov/docs/barttimes/BTimes0707.pdf

[2] http://cahsr.blogspot.com/2009/10/la-sf-nations-second-busie...