One more thing about the politics of the historic June 26 Supreme Court decision and then I'll try to shut up about it for a while:
By early May of this year, several weeks before the Supreme Court decision, Gallup found 60 percent support in the U.S. same-sex marriage with only 37 percent opposed. This is a remarkable change. Just ten years earlier, in August 2005, the numbers were almost exactly reversed, with 37 percent in favor and 59 opposed. (For the May poll see this link. Historical polls are summarized in a table here.)
It's interesting to compare this with the very similar trend line for public acceptance of interracial marriage, as shown in the graph below, originally published in the xkcd web comic last October:
Think about this: As recently as 20 years ago, barely half of Americans approved of mixed-race marriage, and yet it has been a long, long time since any American politician of any consequence, even in the deep South, has been willing to expresses so much as disapproval of interracial marriage, let alone call for making it illegal.
As the old saying goes, it's dangerous to make predictions, especially about the future. (For the possibly Danish origin of that quotation often attributed to Yogi Berra, see this brief report.) But I'll go out on a limb and say I'll be surprised if same-sex marriage is still a significant issue in the 2020 presidential campaign or after. In fact, though it's obviously something Republican candidates are talking about now, it might have largely faded into the background by the general election next year. (When was the last time you heard much about gays serving in the military?)
I would not, of course, expect religious acceptance to come as quickly as political. The Catholic Church in particular isn't likely to change its stance soon, but then again, it still strongly disapproves of divorce, and of remarriage after divorce, and I don't know of any Catholic politicians in the U.S. actively trying to make either illegal.
My previous post on that xkcd graph can be read here, and there's more background, including recent updates, at the Explain xkcd wiki here. For more of my random musings, for whatever they're worth, on public reactions to the Court's decision see the posts here and here.
(Updated 2015 July 15 to add a suggestion that same-sex marriage might largely die out as a political issue before the 2016 election.)