California has the FIFTH largest economy in the world, behind the US, China, Germany, and Japan. It's ahead of India, UK, France, Italy, Canada and Brazil.
California right now GIVES more money to the federal govt than it receives in federal funds. This doesn't take into account emergency disaster relief, though.
California is the the largest agricultural producer in the US and its farmers and ranchers could feed the entire state, meaning that we wouldn't need to import food.
It's pretty accepted that CA, after a period of adjustment & currency stabilization, would be fine as an independent country. One of the main 'issues' would be what to do about the federal lands that are located in CA and establishing a currency.
Because of this, we're in a (hopefully) pretty good position to weather the next four years, economy wise. If Scrotus wants to threaten us with 'no federal funds', Gavin can always refuse to send state funds to DC and instead keep them 'in house'.