Ross Douthat in the New York Times on conservatives accurately predicting what changing marriage will do:

"...the conservative view [of what would happen if we redefine marriage] has actually had decent predictive power. As the cause of gay marriage has pressed forward, the social link between marriage and childbearing has indeed weakened faster than before. As the public’s shift on the issue has accelerated, so has marriage’s overall decline.

Since Frum warned that gay marriage could advance only at traditional wedlock’s expense, the marriage rate has been falling faster, the out-of-wedlock birthrate has been rising faster, and the substitution of cohabitation for marriage has markedly increased. Underlying these trends is a steady shift in values: Americans are less likely to see children as important to marriage and less likely to see marriage as important to childbearing (the generation gap on gay marriage shows up on unwed parenting as well) than even in the very recent past."

... But there is also a certain willed naïveté to the idea that the advance of gay marriage is unrelated to any other marital trend. For 10 years, America’s only major public debate about marriage and family has featured one side — judges and journalists, celebrities and now finally politicians — pressing the case that modern marriage has nothing to do with the way human beings reproduce themselves, that the procreative understanding of the institution was founded entirely on prejudice, and that the shift away from a male-female marital ideal is analogous to the end of segregation.