In Legion, 30 has become the new 90.
The whole probelm with doing the young vs. old thing and stuff like "don't trust anyone over 30" though is it basically presupposes that anybody who's older just plain stinks. I think it's an extremely negative thing to portray and serves only to feed alot of the bad youth-is-king ideas that have caused our culture to basically fear and despise the idea of ageing.
It's a rather interesting development to me.
On the surface, the adults in this future seem to have a lot in common with Byrne's Kryptonians.