Romney could win CA by 20 points and not carry every CD. That being said Romney does have an advantage. He will likely win every CD in the Bay Area (maybe a surprise in the east bay but likely it will just be closer than the rest) and most in LA county where there aren't many Republicans. He will lose in the Central Valley and the Inland Empire outside of the Palm Springs area. Inland OC and LA county will be areas to watch. Still, Romney wins with 10 points even with only Santorum and Paul opposing him and will easily win a majority of CD's.
I agree with this. Like I said before, it was a calculation that I think is a rounding error for all intensive purposes. The geographic area you're talking about is rather vast but sparse; all of that adds up (with the exception of OC) to about ten congressional districts @ 3 apiece. There are certainly millions of Californians extreme enough to go for Santorum but the Democratically-drawn lines do a good job at keeping them divided and/or isolated.
Still, looking at my other numbers, even if you throw Santorum 100 delegates from California, Romney's still going to have major leeway when it comes to getting the combined number of pledged and unpledged to walk with this thing.
I'm pretty sure the new districts will be used, won't they? And they aren't drawn by the Democrats and aren't a bipartisan gerrymander like the current districts. I don't know whether the new lines are more beneficial to Santorum or not. I suspect they are, just slightly. Two districts I can think of that will be more beneficial for him are the Riverside area district that does not go into wealthy areas of OC anymore and the San Joaquin county district that does not pick up wealthy Bay Area suburbs.