Not your problem. Comprende?
The trouble is, there are no red or blue states, it’s more like red and blue counties or towns. The portions of California that area already de facto Mexico (Chula Vista) or hipster strongholds (San Francisco, etc) can go to hell, but there are still many parts of the state with conservative communities. This includes much of San Diego and areas of rural California in the Sierras.
Actually it would very quickly become a problem. Cutting out a cancer sometimes is all that is required but any borders resulting from a CA secession would immediately become like the Mexican/US border with all its problems.
The cancer would quickly metastasize all over the West. AZ, NM, Nevada where would it stop?
Secession is a cancer which once started cannot be stopped.