I don't believe California will be successful if it attempts to secede solo though. I'm going to go out on a limb and predict that if it is going to work, it will need to secede as part of a coordinated action with Washington and Oregon. The end result will probably be a commonwealth of nations relationship similar to the one shared by Canada and Great Britain. I've even got a catchy name for this new nation: the pacific coalition of states, or Pac Coast for short.
I'm also going to go out on a limb and predict that a combination of pushback on federal enforcement of marijuana laws and immigration policy is going to be the match that starts the fire burning. I believe popular pressure on both of these issues is going to force the coastal states to take a stand rather than roll over, and things are going to escalate from there.