California's population is largely stagnant, growing ever so slowly. Who is leaving? Young middle-class professionals are most likely to leave. Who is arriving? Poor immigrants coming from other countries. Which residents are most likely to stay? The elderly. See the story at RealClearMarkets.
The resulting problem? The population is increasingly made up of people who pay less taxes as they are either poor or retired drawing reduced income and paying less property tax via Prop. 13.
Both of these "tax eater" groups utilize more than their share of public resources, while the tax-paying group has moved to Texas and places like it. The state's long term economic prospects therefore are not positive.