As far as social security comes its already fucked up how it is. We are getting money and instead of saving it and investing it for our own generation we are using to to backtrack and pay for the generations retiring. Furthermore, with less people having kids hopefully there will be a simultaneous trend of adopting kids (since they are thoughts not too disparate) from one another instead of having your own. The more adopted kids there are the more kids will grow up in households with good role models and instead of growing up to being a thief because they have no employable set of skills, or resulting to drugs because their reality is too difficult to cope with they can actually produce growth and revenue for the country, at the same time this is less assistance that the government needs to give out.
At the same time with less adults having their own children, and their own worries we will not only definitely have a higher adult : children ratio we might be able to better concentrate on helping this children grow. We now have the same amount of resources being spread among less children so we can focus our attention to areas that might otherwise go unattended the psych of more kids, and their emotional and mental development. The saying it takes a village to raise a child comes to mind.
Seems you are having difficulty thinking outside the box. The population in the USA is rising, so maybe the birth rate is not the only "deposit" needed in the bank. Maybe immigrants paying taxes into the system will be sufficient. And since the unemployment rate is very high, maybe a declining growth rate would reduce the number of people needing assistance, and things will balance out. There are lots of variables and it is difficult to predict the future based on the birthdate alone.
So as of 1:44 PM EST on 8/14/2013, 89% of you are okay with a declining birth rate. So what is your plain to claim me then? Because I only grow if there are new workers. That money you put in, that was to pay for your parents. So if you want to make a withdrawal, you need posterity to make a deposit.
Or maybe you plan on just dying at age 61-66?