Something both religious conservatives and LGBT rights activists recognize is that repealing Don't Ask Don't Tell was never just about ensuring that gay and lesbian servicemembers are allowed to serve openly. It was also about undermining the crumbling logic of denying gays and lesbians the benefits of full citizenship, which includes having their partnerships recognized.
In America, military service has always been a part of how minorities move into the mainstream--the once intractable ethnic differences between whites of different European origins were smoothed over by the crucible of World War II. White supremacists understood the devastatingly clear moral challenge posed by black veterans returning home from the World Wars proudly wearing their uniforms, which was why they so often greeted black veterans with violence. No American willing to take on the most solemn responsibilities of citizenship can long be denied full and equal rights as an American. That willingness to sacrifice onself for something greater stirs something deep within all of us, from the most cold-hearted necon to the crunchiest of dirty hippies.
Sexual orientation is obviously different from race--you can't tell someone is gay merely by looking at them. This is exactly why DADT "worked" in the sense of slowing progress--as long as the sacrifices of gay and lesbian servicemembers were anonymous, that irreconcilable distance between American ideals and the reality of the DADT could be avoided. Shortly after the Senate voted to repeal, David Frum gave a statement to Politico that really crystallizes what the impact will be:
“The military is the most trusted institution in American life...This vote means there will now be a large public population of openly gay veterans, gay combat veterans and decorated gay soldiers and officers, sailors, airmen and marines. That presence is going to be a very large fact on the ground. … People who want to wage cultural wars ought to keep in mind that cultural views often don't move at all for a very long time, but when they move, they can move very fast.”
Things move very fast. DADT repeal, in my view. considerably accelerates the timeline under which same-sex marriage could become legal, both as a legislative matter and as a result of the Prop 8 case currently headed for the Supreme Court. My calculations here are perhaps a bit cynical--I think that when Ted Olson stands before the Supreme Court and rightfully argues that fundamental rights should not be put to a vote, he will be offering Justice Anthony Kennedy an irresistible and historic opportunity to write a ruling that will change American life as we know it--the kind that, from Lawrence to Citizens United, Kennedy seems to really enjoy writing.
I'm not sure whether that'll ultimately mean. When the Obama approach to legislating--making the necessary compromises to get all the relevant stakeholders on board--works, it really works. DADT is dead forever because the military, Congress, and the American people were all on board. If a court had simply overturned the policy, it would have given conservatives cover to support an unpopular policy by stoking a backlash over judges ruling by fiat.
Conservatives and moderates sympathetic to gay rights might argue that the lesson of the long game on DADT is that the legislative route is preferable. But like Scott Lemieux I think the risk of a Roe style backlash is far smaller than people have suggested, for the very same reason that acceptance of gay and lesbian rights is accelerating so rapidly. Abortion, as a medical procedure, remains a much more private matter. The most powerful argument against gay rights opponents has been the visibility of gays and lesbians. Once it becomes a question of not denying rights to some abstract stereotype, but to one's own friend or family member, equal recognition of gay and lesbian partnerships becomes hard to oppose.
I understand the fears of backlash, but I just don't think it's possible for our society to be as divided around same-sex marriage in the future as it is around abortion. There's still a kind of "abortion closet" where people may know people who have had abortions but not know that they've had them making it much easier for abortion opponents to deploy noxious stereotypes about callous, babykilling sluts. But as gay rights opponents are discovering, an increasing number of Americans of all political stripes have openly gay and lesbian friends and family members that humanize the cause of gay rights in a way that neutralizes the typical culture war arsenal. That's why religious conservatives have fought so hard against the normalization of homosexuality, and why they've lost: Because it's normal.