In discussing prisoners that are 100% guilty of violent crimes, meaning video, witnesses, dna, other evidence to be 100% sure of proper conviction. I believe that one day there will be an island or some kind of segregated land mass that we will send those people to survive on their own. It may not happen for many years but i believe that someday society will have had enough of the intentional violent actions and solve it with extreme measures.
They cant claim cruel and unusual punishment because the prisoner themselves made a choice to act in and be in a violent environment when they commited their crime, so we would just be giving them what they wanted to begin with.
We would send them there and they can learn to survive on their own with others like them. There would be no laws unless they make them as a group. If they want someone in charge and others to secure their safety then they create that atmosphere as a group. It would either be that or they can jump off a cliff before hand, up to them. But sustaining violent prisioners at the cost to tax payers i believe one day will end.