'Gender critical' theory. Everyone should have this theory, as originally defined, planted in their head. Men would only associate 'masculinity' with their role in providing semen for procreation. Women would only associate 'femininity' with their role in providing eggs for procreation.
There would be no gender-non-conformity because there would be no ideas about gender to conform to. A minority of men would, as an everyday thing, wear dresses. It would be impossible to verify that someone was a woman or not (short of x-raying their uterus).
The important thing, is that if this happened, the people currently claiming that they're 'gender critical' would lose their freaking minds.
You're reframing OP's question. There's no suggestion that I'm the only one with this opportunity - I'm relying on others to plant ideas about the climate or whatever, and focusing on what maybe other people haven't already said (which is a good strategy for posting on Lemmy, incidentally).
But if that's your genuine criticism, that what I posted can't be ranked as the most important thing, well there's plenty of other posts that you should be busy responding to.
So many relationships would fall apart, so many others would be possible were yesterday they were unthinkable.
So many people would completely lose their identity. And so many others would suddenly feel at peace.
Marketing is completely upended. What even is sexy anymore? To whom and why and how do we even know?
Clothing designers, some will thrive when suddenly it feels as if there are no rules, like you can do anything. Others lose it all together, having no idea what to do.
At the same time, people need to sort people. So I foresee a rise in racism, ageism and other discrimination to maintain largely the same in and out groups. But those first weeks of absolute mayhem that noone understands why it's suddenly mayhem would be beautiful.
It's wild how threatening people find this idea. I really can't get understand why it is so hard to just imagine seeing each person as an individual. No one is walking around dividing the world a priori into "hockey fans or not" and thinking our society would collapse of if you couldn't do that all of a sudden.