Sorry, but the Supreme Court will likely never hear this case. The law, if it passes, most likely DOES NOT violate the Free Exercise Clause of the First Amendment, which only prohibits the government from passing laws that specifically target religious practice. Here, the City of San Francisco has any number of neutral and secular objectives with which it can justify a circumcision ban. As Poppa pointed out, there may be a Due Process claim here, since parents could argue that the law infringes on their privacy. The problem is, Due Process does not protect people from acting in a way that the State sees as harming others in a direct tangible way. I assume the City will be able to provide sufficient evidence that the ban is needed to protect the physical integrity of the child.
Really, the issue is not particularly novel or substantial in constitutional terms, and it will likely go no further than the 9th Circuit Court of Appeals.
The State constitutional claim is another matter entirely. I know next to nothing about California constitutional law, so I can’t comment meaningfully. based purely on the language, however, it seems that the California Free Exercise provision likely provides no more protection than the First Amendment.