I've often said a Republican with genuinely libertarian principles (like Ronald Reagan) could still do well in CA - the problem is Democrats are very good at pretending to be the more libertarian party and the CA GOP is dominated by Romney and Santorum clones who like Big Government just fine. They are just patiently waiting for their turn to take over and run it.
There is no way in hell Ronald Reagan would win California office with the current California voting demographic today. Not even dog catcher. No way in hell.
The conservative electorate that elected Reagan governor and elected him president no longer exists, likely never to return. Hispanics will own the CA voting demographic after 2050 for a century or more.