Regarding...
A large, regional airport at Camp Pendleton, I'm totally for it. It was my favorite realistic option (Miramar is my favorite
fantasy option) during the airport search in 2006. However, Ontario Intl Airport may be a warning for us on preemptive expansion. LAX bought that airport as a sort of annex back in the day, and it never took off as a real alternative for LA/IE/RS travelers. We would need to do extensive studies and research to see if people really would make a point to fly out of northern SD, and so far Carlsbad hasn't proven too promising either.
Closing SAN - not going to happen. A majority of the city loves Lindbergh for it's deficiencies: small size, central location, easy navigation, etc. Selling them on a supplemental airport is a stretch, trying to get them to close SAN would be nearly impossible.
Converting SAN into an urban center: love it, but no. The best we could hope for would be a liberty station-like development. Low-rise construction, maybe 5 stories max. Maybe. Golden Hill residents have been grumbling about Pinnacle on the Park, what do you think the well-to-do in Bankers and Mission Hills would say if they were told their sweeping bay views would be obliterated by a wall of high-rises? It would be Bay Park all over again. I could easily see a Cory Briggs type coming up with a ballot initiative to convert SAN into a park or nature preserve for fairy shrimp. No EIR would be able to support such a massive redevelopment in central AND bayfront SD in an era of rampant CEQA abuses. It's a lovely idea, but I just don't see how you'd get people on board.
Love the mock up though, props to that.