If California wants to go, the US needs to make one stipulation; they have to take Oregon and Washington, as well.
Why give up any territory. Lets make the few blue zones down to the absolute minimum sized liberal/leftist reservations. We can give them security cards and out law self defense "for their own protection" and let them live their non-reproductive lives till they die out.
Ya...we would just let them go. It's what we've always done in the past when states have attempted it.
Cut off SF and LA. Problem solved.
Use the Caldecott as the gateway, in and out.