There is no chance that the Court would hold that DOMA violates the Full Faith and Credit Clause, which unfortunately doesn’t compel states to accept marriages from other states and wouldn’t compel them to do so even in the absence of DOMA. The only possible constitutional challenge to laws like Prop 8 would be that it violates the 14th amendment’s equal protection clause. I believe such a challenge has merit but am quite confident that the Supreme Court as currently composed wouldn’t agree. And because the only Justices who are likely to be replaced during the Obama presidency – at least in his first term – are those to the left of center, there is no prospect that this unfortunate situation will change in the foreseeable future.
Equality of rights under the law shall not be denied or abridged by the United States or by any State on account of sex.