I don't know about succession, but I think California should be divided into two states, North and South. There is nothing about Northern California that is anything like Southern California. The people are different, the geography is different, and the climate is different. When they made California, Congress got lazy and decided to make it one state, because it was easier.
There is a problem with San Francisco. Would that be North or South? Some people there might have a civil war over it, with families divided. That would not be a good thing.