Now that same-sex marriage is all but a fait accompli in the US — come on, do you really think that Justice Anthony Kennedy is going to miss his chance to be the swing vote on constitutionalizing SSM? — it is time to move on to the next frontier: legalizing polygamy. Many SSM proponents have long been indignant that anybody would suggest that legalizing SSM would lead to legalizing polygamy. They’ve depended on indignation to quiet fears of the slippery slope, on the grounds that if people started thinking through the logic of all this, they might not be so quick to support gay marriage.
Well, now that they’ve just about won this thing — and I don’t know anyone on my side of the SSM debate who, at this point, holds out serious hope that gay marriage is not going to be the law of the land soon — it is becoming politically and culturally safer to argue for polygamy. As with gay marriage 10 to 15 years ago, the groundwork for accepting polygamy will be laid by stories and essays in the media seeking to challenge the taboo.
Example 1: Jillian Keenan’s essay in Slate last year: 
While the Supreme Court and the rest of us are all focused on the human right of marriage equality, let’s not forget that the fight doesn’t end with same-sex marriage. We need to legalize polygamy, too. Legalized polygamy in the United States is the constitutional, feminist, and sex-positive choice. More importantly, it would actually help protect, empower, and strengthen women, children, and families.
For decades, the prevailing logic has been that polygamy hurts women and children. That makes sense, since in contemporary American practice that is often the case. In many Fundamentalist Latter-day Saints polygamous communities, for example,women and underage girls are forced into polygamous unions  against their will. Some boys, who represent the surplus of males, are brutally thrown out of their homes  and driven into homelessness and poverty at very young ages. All of these stories are tragic, and the criminals involved should be prosecuted to the fullest extent of the law. (That goes without saying, I hope.)
But legalizing consensual adult polygamy wouldn’t legalize rape or child abuse. In fact, it would make those crimes easier to combat.
Here’s the crux of it:
Finally, prohibiting polygamy on “feminist” grounds—that these marriages are inherently degrading to the women involved—is misguided. The case for polygamy is, in fact, a feminist one and shows women the respect we deserve. Here’s the thing: As women, we really can make our own choices. We just might choose things people don’t like. If a woman wants to marry a man, that’s great. If she wants to marry another woman, that’s great too. If she wants to marry a hipster, well—I suppose that’s the price of freedom.
And if she wants to marry a man with three other wives, that’s her damn choice.
Choice! The Holy of Holies! This is how polygamy is going to become legitimized among the coming generations of Americans, who are terrified of being judgmental.
Example 2: this puffball interview on the Atlantic‘s website today , in which the journalist queries a Brooklyn polyamorous lawyer who fights to advance the cause of polyamorous rights. Excerpt:
Why does polyamory work for you?
I remember from a very young age realizing that I was bisexual, and that I tended to be attracted to many different people at the same time. I really think that polyamory for me is an orientation, like being heterosexual or homosexual. Humans in general have a hard time with monogamy. That’s always been the case. We used to have a sense that it was acceptable for husbands to go out and have other lovers, but with the shift to egalitarianism, rather than to say that woman could do that too, we’ve gone in the other direction.
What are the consequences of that, do you think?
I think it’s interesting to see the way that when people get into a monogamous couple dynamic, they often have to neuter their sexual desires. As the initial intensity of a relationship shifts to feelings of long-term love, you can end up in a sexless marriage, and I think that’s a huge contributor to infidelity and the breakup of a lot of families. We put so much emphasis on a partner being everything—that this person completes you—and when that doesn’t happen it creates a lot of pressure. I don’t think that open relationships are for everyone but it’s something that you should no longer feel ashamed to talk about at a time when so many marriages are failing.
What do your other lovers give you that your primary partner can’t?
Well, for example, with my female partners, I feel a different kind of power dynamic. I feel a protective impulse toward women I’m involved with. It’s a different kind of love feeling. My partner Ed is a wonderful feminist man, though sometimes I’d really like to be out on a date with the kind of man who wants to open car doors for me and treat me like a princess. I don’t want that all the time, but I might want that once a month.
There’s not a single question that remotely challenges anything Diana Adams, the lawyer, thinks, believes, or is working towards. It’s all so cuddly and warm and embracing. Get used to this kind of thing in the media. We’re going to be seeing a lot more of it in the years to come. This is how you prepare the public to accept something radical that would have caused them to recoil in the past. If I were pro-polyamory, I would be working the same angle.
Stage one is to tolerate it. Stage two is to legislate it. Stage three is to make opposition to it intolerable. Wash, rinse, repeat.