One base assumption that may be premature and/or incorrect is that Rancho Cucamonga forever will be its terminus in the LA basin. There have been reports about background negotiations with MetroLink to get from the Rancho Cucamonga area to LAUS, nothing concrete enough to make any announcements, specially since it involves electrification and all that.
But meanwhile, for the time being, Ranch Cucamonga is a heck of a lot better than terminating at Victorville.
OK, I looked at the EIS a bit. On tables 1 & 2, they're claiming a total Las Vegas - "Southern California" Total travel demand of 49 million riders in 2025, ramping up to 63 million in 2044. Total ridership on the NEC, according to RPA, was about 12 million in 2019, the last year before the pandemic. Yeah, Southern California is heavily populated, and the Las Vegas Metro areas has 2.2 million people (about 600,000 fewer people than the Baltimore metro area). There's not much in between except Victorville, which has a little under 150,000 people., so even if it's a high-growth area and doubles its population, that's still not going to amount for a whole lot. And the high desert is really not the best place to start transplanting people in a region of the country characterized by drought.
Aside from New York, Boston, and Washington, the NEC has at least three other metro areas with populations of greater than 1 million, plus a number of other metro areas and cities with populations of 500,000 to 1 million. Nearly all of the larger cities have an extensive ecosystem of mass transit connections feeding the intercity train route, and a long history of the local population using the train as a viable means of transportation. And yet, the NEC only had 12 million riders a year at its peak! I can't believe Brightline will be getting 49 million passengers a year in the first year of its operation, especially since any connections to LAUS or CAHSR is still speculative at this point. Having a terminus in Rancho Cucamonga is like terminating the NEC at Baltimore and Providence and counting on everybody to ride MARC and MBTA into Washington and Boston.
I really don't think they're going to have the passengers to support running high speed trains on 45-minute headways between Las Vegas and Ranch Cucamonga. The NEC can barely do it (and it's not doing it now), and that's subsidized up the wahoo. I'm not even sure how Brightline is justifying the capital expenditure as a private, for-profit company. I suppose they have plans to develop properties by the stations, but I can't see how they can make money running trains over the long term, at least not the kind of money that would interest typical capitalist investors.