Most of the 50's kids are getting old, and not many 50's kids are in the running, just more 40's kids, a few 60's kids, and one 30's kid who has no chance of winning.
So will it happen eventually?
Only on one condition:
If Ron Paul wins the primaries he'll choose Gary Johnson, who was born in 1953, as his running mate. As 77-year-old President Paul will not survive his first term, Johnson becomes the first and perhaps only president to be born in the 1950s.
Perry and Bachmann were also born in the 1950, of course, but there's no doubt that they will lose the primaries or the general election, respectively.