Let's stipulate that the CAHSR thing, so far, is a fiasco. There are many reasons for that. But, let's try a few things on:

Let's assume that the bond measure did not (as it actually did) prohibit spending the money on the main line for anything but True High Speed Rail. Let's further presume (as appears to be happening) that a couple of billion$ are dedicated to "connections," but perhaps to better effect, so key bottlenecks like the run-through tracks would be works in progress rather than wishlist items. That leaves, probably $8B or so plus whatever could have been leveraged from the feds (about what actually happened?). So say about $10-12B. How could that have been better used FOR STATE PURPOSES not just LOSSAN?

A key hole in the state rail system is Bakersfield to LA (Bakersfield to Burbank for HSR). Amtrak will never run on the current Tehachapi line for anything but sanctioned Starlight detours; the freighters won't let them, and the line's too busy and slow anyway. HSR for that segement is expected to cost on the order of $30B - obviously way more than what could have been available. Could a line suitable for Normal Amtrak (design speed, where not excessively constrained by mountains, of 100-125mph) be built over and through the Tehachapis, usable with diesel locomotives (so, no long tunnels or very steep grades), for $10-12B? Such a line seems likely to have run over the Tehachapis somewhere near the existing line, and down along the SP to connect with Metrolink - not to keep Palmdale happy, but to minimize the amount of work needed. Some improvements to the Metrolink AV line would then be needed to improve speeds and capacity.

The North End probably wouldn't need much for a while. There are already rail lines into the Bay Area over Altamont and through Martinez that do the job for Amtrak. Perhaps an express line could be added along the old West Side alignment, but that's not an immediate high priority and after getting over the mountains there probably wouldn't be money anyway. Improvements in the Valley could have been incremental, aimed at reducing bottlenecks/freight interference and making higher speeds possible. Something like the HSR line (though at a lower level of engineering) would eventually have been needed through Fresno, at a cost of a couple of billion$, to improve speed and reduce freight interference.

As an alternative, would a fast (not High Speed, but fast) line along the Coast have been possible for the money needed to get over the Tehachapis? I'd define "fast" as less than 6 hours from San Jose to Burbank AKA driving time when I-5 behaves. I'd note that the Coast has a few geographic issues, like Cuesta, the sea level running in Elkhorn Slough, and the seacliff and sea-level running along the Santa Barbara-Ventura coast, that could cost a lot of money to deal with in a semi-permanent fashion given sea level rise and general geological orneriness (not that getting over the Tehachapis is a piece of cake...). LOSSAN, of course, has a few similar spots though not, probably, of the same order of difficulty (and the basic studies are already done so there are fewer unknowns, which means more predictable costs).

Anyway, thought experiments, and should any of this someday make it into the state rail plan with or without HSR?

Also notice, I completely ignore national Amtrak. The current crowd will have it on its last legs by 2020, and if T is reelected there won't be anything left of it by 2024.