Yes. Absolutely. I think most child-men will grow up. And they are growing up. I hear stories all the time of the Maxim-reading-beer-pong-playing-frat-boy who turns out by thirty to be a mensch of a guy. But the danger is this: that guy, if he's waiting until his early thirties to become a mensch, the women who are his age are in a different place than he is. Also, to get back to the biology, it is simply a fact that men have an increasing pool of available women as they get older, and women have a diminishing pool. And that's just math. On average, men are more interested in younger women, but not older women.
Another bit of math affecting preadulthood: 58 percent of our college grads are women, which means a great deal of women are going to have a hard time finding a college-educated spouse. And many women don't want to marry "down." Will they do so in the future? I suspect that a lot of them will decide to simply have children on their own.