Sadly unlikely, R57. We could be shocked by the outcome, but probably will not be.
But if the DOMA case is a win for us, it sets the stage for full faith and credit cases in recognizing gay marriages federally and state to state, which could be the battleground case of the future (states have the right to make their own laws but generally recognize marriages in other states, even if they have different age limits, etc. -- it could be a Romer violation to say no.)
A gay couple married in Canada can move to a state that recognizes marry in a state that recognizes gay marriage and will get federal benefits.
But for the rest of the country...
If you look at the trilogy of cases most relevant in politics if not law -- Loving v. Virginia, Bowers v. Hardwick, and Lawrence v. Texas -- the Court favored rights in the first and third after most states had already gone in that direction, whereas in Hardwick the Court split 5-4 and specifically claimed it wasn't going to go against the half of the states that had sodomy laws at the time.
The Court doesn't want to move too fast, and if the Court at least lets the lower courts stand in Prop 8, it's better than the nightmare scenario that Lambda worried about if the case was brought too fast -- that the Court would come up with a homophobic ruling, and from the digs Scalia took at oral argument, it looks like that's why the Court took cert, because the conservatives wanted to make a statement and convinced Kennedy to go along, who seemed to have regrets by the time oral argument went around.
In other words, it wasn't the progressives who wanted to take the case to make history. Even Ginsberg has said with regard to Roe v. Wade that she wonders if the Court went too fast ahead of the nation in making a broad ruling.
So yes, this will actually force gay people in the horrible states to take drastic steps -- move even if it's a hardship -- or fight harder than ever to get rights.
And we'll see, as Britain gets same-sex marriage democratically, if the US starts to see itself as backward...