California has four, for now. The Raiders aren't leaving due to lack of a fan base. Oakland and their tax base, wisely won't pay for a stadium and Davis can't afford one.
The Chargers should suck it up, do a full on mea culpa and go back to SD. The town will forgive and a stadium deal will, eventually be reached. Unlike Oakland, San Diego is a legit tourist destination (sorry Oakland got nothing but mad love for.you but it's true) and some kind of hotel tax can be the primary driver to finance the deal... providing the surviving Spanos's get their collective heads out of their ###es and pony up. Unlike Mark Davis, they can afford it.