I would estmate about the same number (200) of PCUSA churches will leave soon after the local option on ordaining homosexuals is approved.
A couple of presbyteries will vote to approve the dismissal of all the churches within their presbytery and most of them will leave for greener pastures and the remainder will vote themselves to return to the PCUSA.
Other churches will leave by themselves.
Most of the PCUSA churches will continue to have their false hopes that the future will be well and will stay with the denomination. Our prayers go these churches with their head in the sand. They truly must enjoy reading bad news about their denomination every day.
San Diego was my first thought when I read that, but I can't really think of a second.