The main thing that makes this interesting is Roe vs Wade, which protected the right to abortion forty years ago -- but the country remains split even now, and a surprisingly even split at that, over whether or not abortion should be forbidden/restricted.
It feels to me like, one way or another, gay marriage is going to be accepted and legal in most if not all of the US within the next 10-20 years. Despite some early legislative opposition, the tide seems to have turned now, and I think that turn is permanent, just like the turn in favor of mixed-race marriages in an earlier era. This is the right side of history, however people may feel about it now. I am very happy about it, myself.
That Roe vs Wade analogy does make me wonder if the method by which it becomes legal will make a difference in the long run. Probably not -- I don't think it made a difference with anti-miscegenation laws, which were also overturned by courts. But it's an odd idea to contemplate, that letting a question be settled at the ballot box might promote a more lasting transformation in civil society. Or that judicial rulings might prevent the same. It has a certain resonance as an idea, a feeling of truth, though I don't know that there's any evidence it is.