For me age isn't really the issue, Dredd should just get more interesting, his weaknesses should become plusses for the story. I find Dredd more interesting as the years go on, though Wagner only gives us tantalising glimpses of him. Maybe thats why they are so enjoyable.
I still say that for me the ultimate journey for Dredd would be one where he ended up a family man, with kids on a cursed earth farm. Yeah he can kill dinosaurs, but there's a big part of me just wants him to get a wife and kids and enjoy life.
Having said that, I want to outlive the bastard.
As far as younger heroes go, well, what do you want? Dredd, Rogue and Alpha were never youth culture twats like Sin and Dex.