Yes...I agree that any EAT-OAK would definitely have to heavily subsidized. However, I don't think LF will go to ACV because of the proximity of CEC. I think there is some traffic that CEC is seeing is coming from ACV, since it's only an hour or so away.
I still think it would be natural to see LF fly the SBA-SJC route eventually.
ACV has service to SFO, so they don't need to drive up to CEC to fly to OAK. When PenAir first started CEC-PDX, people were indeed driving up from ACV, and continued to do so after ACV-PDX started because the subsidized CEC fares were much cheaper. (Btw, it's 1:40 drive airport to airport when there aren't big delays on US 101 ..crumbling cliff road.)
No here, I'm thinking a through trip CEC-ACV-SMF as there is no service in that direction. UAx/OO used to do it until OO retired the Brasilias. The schedule then didn't make a North Coast-Sacramento day trip possible, something LF or any successor should consider. And it might need interline connectivity to fill the planes. It's not out of the realm of possibility, as LF is now in SMF. The difficulty would be supporting a light load on the ACV-CEC-ACV tags, as ACV would be generating the larger portion of traffic. And then there is the fog.
SBA-SJC does make sense if well scheduled. With SBA-SFO/OAK existing, SJC would need well timed flights for business folks, at either end of the business day in order to compete with the nearby other routes. I don't know if anybody has been steady on the route since Apollo/Pacific Coast, which had 4 -5 Jetstreams daily, and covered both business and leisure times. I do think I remember AS*/QX trying a SMF-SJC-SBA run, but that was not successful, and didn't last long.
The trick is LF having enough aircraft and crews to serve our dream lists.
Worked for WestAir, Apollo Airways, Desert Pacific, Western, AirCal and American Airlines (Retired). Flight Memory: 180 airports, 90 airlines, 75 a/c types, 403 routes, 58 countries (by air), 6 continents. 1,117,006 passenger miles.
Home airport : CEC