If it was that cheap and fast I'd think nothing at all about travelling between the cities a couple times a month. Not daily, but far more frequently than I do now. I wouldn't be the only one.
Beyond that, the paper also claims a total annual ridership of 7.4 million people, so approximately the same ridership as currently served by air travel. So, other than acting as a jobs program, in what way will this alter the economic landscape of California?
Given how fuel dominates the cost of operating an airline, I'd say that something that is net neutral in terms of energy usage should be able to compare quite favorably in terms of marginal operating cost. I think that that $100 each way figure is very conservative in terms of what it would cost to transport a person.
I'd say the ridership assumptions are very conservative, the experience described is so much better than flying that I would guess that ridership will increase quite a lot. I would visit LA many times as frequently as I do now. It should also cannibalize car traffic quite a lot.
As far as economy goes, this would make intercity business much easier, decrease congestion of the freeways, save many man-years of time that would be otherwise spent in airports or driving, and it would be generally more efficient.
Edit: more like 6 million people fly between LA and SF annually. I was thinking of the Amtrak Northeast Corridor ridership, which is about 12 million annually.