Constitutional protection exists now! The Equal Rights Amendment was proposed with about the very language used for race and religion. In legal terms, any classification by government based on gender, would be treated with strict scrutiny. The burden is on the government to prove they have a compelling justification for the classification and that it actually exists. Justification cannot be enough. Past const'l amendments took quite a while to make the rounds of state ratification. Recent amendments, though, were ratified quickly.
The ERA sailed through many legislatures. Almost 3/4 of the states had ratified it with no meaninful debate. Right wing groups started arguing falsey that it would harm women. It would have removed almost all pedestal legislation. These laws supposedly placed women in a better position b/c they raise children and are weak. An example is women not serving in the military or on juries, even when they want to serve. The Roman Catholic Church felt threatened. Conservative states still not ratifying had long debates and no further action was taken. Some states that ratified it without debate retracted their ratification. It was never determined where such retraction is possible.
This easy political battle became a horrendous mess. Feminism was strong, though, and much progress was made in educating people concerning feminist ideals. Most people believed in equal rights even if they felt an amendment was too much. Generous laws were enacted.
The Supreme Court justices are married and have daughters. Over time, gender became an intermediate scrutiny method. The burden was on governmen to prove an important goal, not otherwise able to be carried out. The shifting of the burden from plaintiff to defendant meant women starting winning in great numbers. Since the Supreme Court already ruled in many cases that gender was almost like race and religion, activists decided not to press for the ERA. Theoretically, some cases might have been decided differently but they are rare.
I worked on some of these Supreme Court cases in law school and afterwards. It has been a while. I could write about it much more persuasively then. Wikipedia prob. has a much better article than what I've written.
As a poli sci matter, I see the role of the Court in reaching to accomodate a politcally disadvantaged group. The const'n did not change. They changed its interpretation. The amendment's language was so simple. It showed the power of the right wing to stop social progress. Life is so different now. We never needed a pedestal, only a fair, equal chance. Men still earn far more per hour for comparable work. I've read that fewer men go to college now than women do. Sort of Dylan, who is the first will later be last, the times they a changin'