One would hope that we no longer celebrate nuclear warfare with a ring for children.
These conical hennin hats were worn after plucking out any forehead hairs to make the forehead look very high. I don’t see this trend returning although the thinning of eyebrows comes and goes. Here is a fascinating read about hennins.
Likewise, powdered wigs were worn by the nobility because some of them were bald and bald was considered bad.
Dangerous public playgrounds will probably not make a comeback but in this climate of deregulation, perhaps…