People would develop in different ways if they could live to be 1000. It would hardly end societal development. I imagine education would be a bigger deal, since you'd be in less of a hurry to get on with life at 18. Families would be larger as more generations were included, which could create more nurturing and supportive environments for at-risk children. You'd also have fewer trust fund babies living off of the inheritance from a dead relative. And the sheer amount of brainpower and life experience we lose every time a 90 year old dies is depressing; science, technology, and literature could all benefit from people living longer.