Supreme Court did not strike down Proposition 8. It merely ruled that those who sued and brought the case to the Court had no standing to sue.
As I understand it, the case was appealed directly to the Supreme Court from a California lower State Court that invalidated the Proposition. If that is the case, the petitioners still have the right to appeal that lower Cort ruling to a California State Appellate Court to try to overturn the ruiling and if not successful there then to the California Supreme Court.
So, again if that is the case, the whole thing is still up in the air until it works its way up through the Califronia Court system. It could then again go to the US Supreme Court. Maybe by that time, the proponents of Prop. 8 will have figured out who should bring the suit and appeal so they would have standing before the USSC, in which case the Court would have to either outright reject it or hear it and make a final ruling.
I don't hold much hope of success, since the inmates are now in firm control of the asylum.