It would be nice if younger people (say, sub-70) would (and could be permitted to) take up the mantles of leadership. I'd really like to read a speculative fic

It would be nice if younger people (say, sub-70) would (and could be permitted to) take up the mantles of leadership. I'd really like to read a speculative fiction/scifi where every generation operates under its own system of laws, and you can opt in to a neighboring generation's laws instead once every N years or something.