With no plans to go to the moon again, we will soon be out of living moon-walkers.
xkcd ran the numbers: http://xkcd.com/893/
"The universe is probably littered with the one-planet graves of cultures which made the sensible economic decision that there's no good reason to go into space--each discovered, studied, and remembered by the ones who made the irrational decision."
Personally, I'm optimistic that there'll be boots on the moon sometime around 2020 (although I suspect they won't have NASA logos on them). Looks like there will be 2-6 moonwalkers left to see that, with a 90% confidence interval...