They'll do a study on this by studying Japan, but a better place to study is France. Or even Europe altogether; the high-speed part here is a red herring, what matters is seating-room, few-transfer commutes of tolerable duration to outlying towns where road-bound price pressure doesn't currently extend. Many countries in Europe accomplish this with trains of "conventional" speeds.

On the other hand, it's hard to argue that places like Tracy, Stockton, Modesto, and Sacramento aren't already in the gravitational pull of the Bay, or Lancaster and Palmdale aren't already in the commuter belt for LA. Desirability in these places is likely to rise with the option to trade a long car commute to a shorter P+R train commute.

The toss-ups are Bakersfield and especially Fresno. These are metros far removed from others, can't significantly interface daily commuters with others, so their housing and job markets stand on their own. But for the same reasons, among California metros they're also the least subject to existing affordability crises. If their access to the Bay and LA improves, this will change -- and already-sprawling, already-transit-poor Fresno and Bakersfield can hardly distribute this rise in demand evenly in their grid.

EDIT: 'Organic' affordable housing has always been greenfield, because it's cheap to turn peripheral land to inexpensive dwellings. But HSR will serve built-out city centers, where expensive redevelopment is required if one wants to satisfy demand. And if the demand is there, the asking price will reflect that.