
So if aging is gonna be gone, anyone wouldn't be born anymore (could a fetus grow without aging?) or if so they would be eternal babies.
Plus the only adults left even without aging they would still be mortal, so it would be the end of the humans either way.
Or a future world ruled my babies maybe?

If their minds develop then maybe but if the mind developing is part of aging then no because baby's mind's develop to do a lot of things like motor skills for speaking and holding things, identification, abstract concepts so they would be forever babies.
Unless fujimot just decides to say "fuck it"
He lost everyone in the first part he loved, then the only and last reason he endured for, Nayuta, got killed too.
He's constantly missing powder, remembering her, how his friends made existence enjoyable.
He's watching the whole world fall apart, alone, while everyone hates and fears chainsaw man.
He can't enjoy what he always strived and fight for, a normal boring secure life, he can't neither enjoy what being chainsaw man means in terms of, how it's consequences fuck everything and everyone around him, how everyone wants to manipulate and use him because of it.
Honestly, he's just broken and alone, missing those he lost, he just wants to be loved, and he's being constantly used and manipulated by that need, like its a weakness.
I really don't know where Fujimoto is driving the story to, but I'm really looking forward to see Denji and the blood demon meet again.