Tyler Cowen entertains the idea:
I predict many people would become much stricter in their morals and more religious, and they will have children quite early. Other people would attempt to maintain a collegiate lifestyle through their death at age forty. There would be a polarization of outcomes and approaches to life. Old age as an equalizer, and as an enforcer of responsible savings behavior, would be gone. The likelihood of warfare would rise, if only because the sage elderly won’t be around and male hormones will run rampant.