Carousel was fine, but ultimately just kicks the football down the road again. You can only band-aid the age issue so long, until it raises more questions then it answers. Lest we forget 50 Year Man addressed the issue too. But that wasn't enough.
Like, why would Justice Department let any Judge retire to teach at the academy/take the long walk, when they can just deage them? Cost and because Dredd's a special case? Okay. But we've seen Cits use this kind of tech before too. So it can't be that rare/expensive. World inconsistency for plot armor, that's a big pet peeve of mine.
What I'm saying is, there's an interesting story somewhere to solve the problem. One that doesn't involve deaging tech, replacing him, or killing the guy off. I minor epic that leads to a near death Dredd having to have his brain transplanted into a brain dead Rico or something. That'll give the old man another 40 years before its a problem again, easy.