Too bad the majority of the US's Western fleet is based in San Diego.

Unless they are magically caught unawares all in port, they will just get shifted to the other pacific bases. Even if they are somehow magically instantly destroyed when California turns traitor you have to consider the other two major naval bases in the Pacific

Naval Station Pearl Harbor:

• 2 Cruisers

• 9 Destroyers

• 18 Attack Submarines

Naval Base Kitsap:

• 4 Aircraft Carriers

• 1 Attack Submarines

• 10 Ballistic Missile Submarines

Russian Pacific Fleet:

• 1 Cruiser

• 5 Destroyers

• 13 Attack Submarines

• 10 Cruise/Ballistic Missile Submarines

So in a worst case scenario the Russians are still looking at throwing 1 cruiser, 5 destroyers, and 13 attack submarines up against 2 cruisers, 9 destroyers, 19 attack submarines, and 4 supercarriers. This is only for those two bases and doesn't consider any other ships the US has in the Pacific. There's zero chance that California isn't getting permanently blockaded.