With regards to the subject of the OP, I tend to think that the world is already too overpopulated, and thus people having fewer or no children would be ideal. I don't think a significant decline is too likely, however, as a lot of people do want to have children -- often for the wrong reasons, IMO. Don't misunderstand me, I'm sure many people (including some on this board) have children because it's what they want, because they feel that it will be a blessing and that they have a lot of love to offer a child. However, I believe that many people have children simply because it's expected of them, either by society at large or by their family members.
For instance, I have an acquaintance who is married with two children. We once were on the subject of marriage and children, and he admitted to me that, although he loved his kids, if he had to do it over again, he probably wouldn't have had any. At the time, he felt that procreating was the next logical step, that it was what was expected of him and his wife, so they went ahead and did it. And now he realizes that he probably would've preferred staying childless, but what can he do about it at this point?
Myself, I'm pretty much indifferent to the notion of having kids. I figure, whatever happens, happens. Of course, if I did have children, I'd first need to find a woman and get serious with her (highly unlikely) and get a steady, well-paying job so that I could support my family (also highly unlikely, since I'm a bit directionless, at least right now). So it would seem that the odds are against me reproducing... and I'm fine with that. I don't think I need to have children for my life to feel complete. The irony is, I actually think I'd make a fairly good father, but I'll just settle for being an uncle/older cousin/occasional babysitter.
I've mentioned to my parents that I consider it unlikely that I'll ever have children... I think they're a little disappointed to hear that (which kind of goes back to the expectations of the family that I mentioned above); I'm pretty sure they want to be grandparents someday. I told them, hey, they've still got my sister, who does seem to want children at some point, but they're a little skeptical of that happening (they seem to think that my sister, being gay, might have difficulty finding a partner that also wants children... plus she's not exactly sure, if she were to have children, how she would go about doing it, i.e. adoption, artificial insemination, etc.). So yeah, my parents are a little worried about their genes ending with us... oh well, too bad for them.
