The challenge is social acceptability rather than legality. Being topless in public is already legal in most of the US. It's our culture which hasn't budged since the 60s (and in fact has regressed in a lot of ways).
I'd argue it has more than budged, it's moved dramatically. I know several people who make amateur porn. These are professionals in tech! I know an ever-growing number of people who are in non-monogamous relationships, who defy traditional gender roles, who embrace alternative/kinky sexuality and who in some cases are raising their children in homes accepting of all of these things.
Cultural norms were vastly more oppressive and restrictive in the 1960's. And in the 1990's.
