As a side note, the development of the corridor would not only improve connectivity of Central California residents to the Bay Area and SoCal, but also to the Sacramento region. Although the Capitol Corridor does reach Sacramento via the Bay Area, this section is crowded by commuters and the train must navigate the slow curves of San Pablo Bay west of Martinez. From the thumbnail above, someone in SLO might have a quicker journey to Sacramento via Paso Robles and Hanford, bypassing the Bay Area entirely.
The inland town of Hanford is presently served by the San Joaquins but is also home to a future High Speed Rail station, as part of the first operating segment from Bakersfield to Merced. It is reasonably expected that when that high speed section is complete, travelers from the Paso Robles bus can board a high speed train north to Merced, with a cross-platform guaranteed transfer to the conventional San Joaquins train waiting at the station to continue north to its existing destinations of Sacramento or Oakland.
Though as it happens, the San Joaquins itself is pursuing an expansion to the north, beyond Sacramento towards Chico, overlapping communities which are served only by the two one-way Coast Starlight trains. This expansion will use UP’s Sacramento Subdivision that runs north-south.
An odd quirk of Sacramento is that the principal train station sits only on UP’s Martinez Subdivision, which runs west to the Bay Area and east to Reno. The only junction between the Martinez and Sacramento subdivisions is Haggin Junction east of the station. But Haggin is not a complete junction, and northbound traffic on the Sacramento Subdivision must pass north of and then reverse into the junction to enter Sacramento station to the west.
This is not ideal for the San Joaquins northern expansion, and so they’ve decided to outright skip the main Sacramento station in their plans. Accordingly, for someone in SLO heading to Chico, it is indeed more advantageous to travel inland by bus and then train, to avoid the Bay Area congestion and a connection from the Capitol Corridor somewhere in Sacramento. But for a destination east of Sacramento, the Capitol Corridor route would be more advantageous.
No plans exist to upgrade Haggin Junction, nevermind the disruption it would cause to downtown Sacramento. Instead, the transfer to Sacramento station would likely happen from a new San Joaquins station linked to SacRT’s Gold LRT line in Midtown Sacramento.
As for why San Joaquins couldn’t expand operations on their already-occupied Fresno Subdivision and has to build these new stations just to head north, it is because the Fresno Subdivision is at max capacity, and because turning north would require a brief traversal west onto the Martinez Subdivision, until turning north at Haggin Junction. This is too much impact for UP to accept, in addition to wholly bypassing the communities between Lodi and Sacramento which don’t yet have passenger rail service, even though they see freight trains on the Sacramento Subdivision.