Cultural event
Most golden age heros have retired by now, not just because of age but also super villainy decreased.
It has been 15 years since the end of the war and 18 since the appearance of the first Canadian superhero. Black Knight and the Polka-Dot Pirate are the the youngest known heros and by know they are in their 30's. Many of them do not have the abilities or physiology to continue going so many retire. Everybody deals with the change their own way. Some retire peacefully while others struggle with it. It is also the time of Quebec's Quiet Revolution, an important time of the change in the province. In a way this moment of time is symbolic and thematic, things always change and have to change and so to must the heros.