Pretty much like I predicted: DOMA overturned, and Prop 8 booted because plaintiffs lacked standing.
What happens next: Since the Court ruled that the federal government cannot discriminate against same-sex marriages under the Equal Protection Clause, all the remains is for that same reasoning to be applied to the states. After all, states cannot violate the federal constitution either. So some new case must work its way up through the courts. It will probably be a case where someone was married in, say, Massachusetts, and then moved to, say, North Carolina, and was denied some state benefit relating to marriage.
Or it could simply be a case where a gay couple tried to get married in a state not recognizing gay marriage, and they are denied. They sue the state saying it violates the Equal Protection Clause.
Either way, this is the beginning of the end.