Hey! Hey!! If you're going to strangle me, I'm going to put up a
mean fight! 
If there are disproportionately fewer births, when they reach
working age, economically, they DO have to end up supporting the
elderly population by way of taxes, volunteer work, etc. Resources
WILL continue to be channeled to see to the welfare of the greying
population and the burden shall continue to be shouldered by the
economically viable, ie. those who are still working.
In demographics, we always avoid a top-heavy age pyramid, because
it means that those below, shall shoulder a heavy burden.
There ARE social costs and implications involved!
Japan even produced a documentary back in the late 90's on their
greying population. They were studying ways on how to handle the
economic and societal implications of a large greying
populace.
If birth rates do not have serious implications on Singapore's
future, then, why would the govt go to such extent to try to
encourage more births?