That's sort of what I had in mind actually. The government builds a retirement home for superheroes and supervillains and then stuffs them all in there. Everyone still has their powers, just maybe less powerful or less reliable (for example cyclops from X-men is losing his eye-sight so his lasers are now more akin to really bright flashlights or spider-man has arthritis so his wall-crawling is either really slow or he gets stuck sometimes), and they all still have old grudges and habits so you might have Von Doom running around building evil robots out of kitchen appliances and unleashing them on the nursing staff or something.