Actually one of the biggest problems humanity will face in the future is not enough people.
The tech billionaire said low and rapidly declining birth rates are "one of the biggest risks to civilization."
www.google.com
I don't agree with everything Musk says but he is on point about this. Birth rates in the first world are in decline and even large developing countries like China are going to experience a rapid decline in population. In fact by the midway point of the 20th century only Africa countries are projected to experience population growth.
They clearly indicate that it would extend all periods of life. Basically you'd be a teenager till your 30 and by the time you hit 50 you'll only be say 30 biologically.