I don’t really see it as inevitable at all. We can estimate travel times along that spine, using current projections and a little back of napkin math:
Vancouver - Seattle: 1:00
Seattle - Portland: 1:00
Portland - Sacramento: 2:30**
Sacramento - San Francisco: 1:00***
Sacramento - Los Angeles: 2:20
Los Angeles - San Diego: 1:20
** 2:30 for Portland to Sacramento is generous, considering the mountainous terrain would likely bring down average speeds by quite a bit, but this is just a thought exercise.
*** I’m estimating an hour between Sacramento and SF assuming trains would use the planned Merced County wye. This could be significantly shorter if a second Sacramento to SF leg is ever built, but none is planned.
Vancouver to San Diego would clock in at ~8 hours, 10 minutes.
Trips from SF would be ~3 hours, 30 minutes to Portland, ~4 hours, 30 minutes to Seattle, and ~5 hours, 30 minutes to Vancouver.
Seattle to Los Angeles (which I assume this would be the highest demand route along the corridor after LA to SF and LA to SD) would clock in at ~5 hours, 50 minutes.
For HSR to take hold, it needs to be competitive with the alternatives. These HSR travel times obviously blow car travel out of the water, and for some of the shorter trips (Northern California to Southern Oregon, for example) I foresee them taking plenty of cars off the road. But it’s hard for me to see droves of travelers opting for a four-and-a-half hour train ride from SF to Seattle when a two hour flight is an option, or a nearly six hour ride from LA when a three hour flight is an option.
Price could be a deciding factor; both the cost of the system and the cost to consumers. That mountainous terrain between Shasta and Eugene is hard for me to look past. It makes tunneling from Burbank to Palmdale look like kids’ stuff, and I’d expect a crossing to cost tens of billions. And as a rider, does that get baked into the price of my ticket?
My hope is that regulators start making regional air travel much more expensive as these systems start to open up. Levy taxes and fees on short distance air travel and put that towards the construction, maintenance and operation of HSR, and subsidize train tickets (not unlike LA’s proposal to use congestion pricing for cars to finance Metro projects).