The legal status of a topless citizen in a public space, regardless of gender, depends upon a community’s standards for public nudity.
Some localities (Denver, NYC, Miami) already allow all citizens to be topless in public.
Most localities in America restrict toplessness for women.
A community’s public decency statutes are not likely to be impacted by the 28th Amendment (Equal Rights) because:
Constitutional amendments have limits, and rights do not exist in a vacuum.
Public decency laws have been upheld by the Supreme Court even when challenged as violating the Constitution’s First Amendment guarantee of freedom of speech. A well known example is that it’s not legal to yell “Fire!” in a crowded theater (if there is no fire) despite the right to free speech.
When the 28th Amendment is enforceable, the government can still pass sex specific legislation if it has a compelling government purpose and the government action is narrowly tailored to achieve that purpose.
Further, public nudity prohibitions have not been held to this exacting standard. For example, the Supreme Court has already recognized nude dancing as expression protected under the First Amendment while simultaneously upholding enforcement of public decency statutes because the public decency statutes are necessary to serve a substantial government interest.
In other words, the Court allows state governments to restrict fundamental First Amendment rights in certain circumstances. These cases provide a basis for applying a more lenient standard to test and uphold public nudity statutes challenged on equal rights grounds.