- In gay-marriage states, a large minority people committed to traditional notions of marriage will feel afraid to speak up for their views, lest they be punished in some way.
- Public schools will teach about gay marriage.
- Parents in public schools who object to gay marriage being taught to their children will be told with increasing public firmness that they don't belong in public schools and their views will not be accomodated in any way.
- Religous institutions will face new legal threats (especially soft litigation threats) that will cause some to close, or modify their missions, to avoid clashing with the government's official views of marriage (which will include the view that opponents are akin to racists for failing to see same-sex couples as married).
- Support for the idea "the ideal for a child is a married mother and father" will decline.
I think this list doesn't even pass the smell test. I knew a lot of kids whose parents believed in creationism over evolution and, while the school board didn't exactly oblige their beliefs, I never heard any stories about them being told that they "don't belong" in public schools. And I think #5 is dubious as well. It's unclear what percentage of the population is gay, but it's almost certainly not higher than 10%, and probably not higher than 5%. That's 5% of people who are already in committed relationships, living in committed relationships, adopting children, etc. The cultural shift has already happened, and what the SSM battles are about is formalizing these changes. The heterocentric view of marriage will still (appropriately) be predominant, and SSM will be merely a caveat. That seems about right to me. And the notion that "the ideal for a child is a married mother and father" will decline because of SSM, as if it is in ascendance now rather than in an extended period of decline anyway, is silly as well.
But the problem here, as it is in much of the mainstream right, is that it personalizes the political to too great an extent, and also that it's highly solipsistic. Has any of this stuff happened in the six states that practice gay marriage? No? How about D.C. and New York, which recognize other states' same-sex marriages? I haven't read any news stories to this effect. And I haven't heard of it happening in the dozen or so countries that have legalized it full-scale. South Africa seems to still be heteronormative. What this is about, of course, is it's more about the right-wingers themselves, who evidently feel that the legitimacy of their social issue stances is predicated upon widespread acceptance of those stances. This boils down to a lack of faith in those stances in general, and that lack of faith is indeed warranted. You see this in that list of reasons above--indeed, as Kevin points out, all of the reasons boil down to "people won't like us anymore". Conservatives might pay lip service to the notion of the sanctity of marriage, but they have held power for most of the last generation and they didn't actually do anything to try to help it in terms of policy, or even to educate people on the issue, aside from frequent attacks upon liberals as "destroying the family". Seems to me that the highly-individualistic, materialistic elements of our society--which the right doesn't seem to condemn--are the real culprits here, but that's just a theory. In the end, conservatives' interest in durable marriage extends no further than extolling it because it's part of their identity. The right, at this point, is merely a bubbling cauldron of identity politics, nothing more.