Oregon is already working on a ballot initiative, so California won't be going alone.
The comparison to the southern secession is interesting, but it breaks down at the stupidity level. The north needed the lock on southern cotton that a united country gave them. They knew it, so they wouldn't let go. California is the economic engine that provides the wealth that keeps the dim and destitute afloat, but the dim and destitute are stupid and don't understand reality. They can easily be manipulated into "better off without you, so go." The only problem will be that when the RSA (Remaining States of America) realize that letting 10% of the population leave with 20% of GDP was a really stupid play they will likely go to war after the fact.