I think it's obvious this is already changing rapidly. Maybe certain antiquated standards of masculinity still reign supreme in rural Indiana (or wherever), but in major metros there is an constantly expanding spectrum within which gender can be expressed without drawing criticism.

It may be unusual for a man to stay home and take care of the children while his wife works. But the idea that I could ever stigmatize or criticism someone for this life arrangement is ridiculous to me. I'm sure that 40 years ago most men would only be able to respond with criticism. But these days that kind of reaction is laughable. And the men who have that kind of reaction would be viewed as backwards simpletons.

I think a growing cohort of men will start to live their lives and express themselves in ways that are fulfilling to them and know it’s worthwhile despite society’s expectations. This might involve being more “feminine” in a lot of ways or place less importance on their careers or seeming successful by traditionally masculine traits. I think men will recognize this in each other and support one another when their peers or women won’t necessarily like the untraditional new lives they’re leading. This might be like women having careers in the 1960s or LGBT people being out in society. It can be untraditional, but ultimately a fine and healthy way to live your life. I think social media or online communities will help with this too.

In terms of what is causing it to change, I think is deindustrialization and the nature of a capitalist, individualist society. If your peers or culture are asking you to be “masculine” as a hunter gatherer, Breton-Woods-era American tradesman, or Jay Gatsby-type, you’re going to feel out of place if you don’t feel like that’s how you want to live your life.