Rubio would get between 51-54, Hillary 45-48. Very static and polarized county now, not much room for movement on either side.
I don't know why everyone is assuming the Asian and Hispanic vote won't swing and is static. I know that subsample margin of error plays a huge role, but the Hispanic and Asian vote seem to be pretty swingy to me. And those Asian and Hispanic swing voters will live precisely in an area like Orange County. Places like Irvine (for Asians) or Orange/Placentia (for Hispanics) come to mind. Of course if Trump is the nominee, I wouldn't be surprised if the great OC votes for Hillary.