Well, we could look to both the legal and medical professions.
For example, back in 1970, about 8% of all doctors were women. Today, roughly 1/3 of all doctors are women--hardly parity, but a significant improvement, nonetheless. Similarly, about 1/3 of all lawyers are now women; back in 1970, that number was closer to 5%.
So what happened between the 1970s and today in the legal and medical professions? For one, there was a concerted effort to even make these professions accept that there was a problem. In both the industry and the public eye, it was generally accepted that women weren't lawyers or doctors because women simply weren't cut out for that kind of work--it was too demanding, too rigorous, too technical, too high-stakes, and required an 'instinct' that women just generally didn't have.
Additionally, there was a very active and ongoing effort to encourage women to enter these fields--efforts that took a long time to gain steam, as these fields require years of specialized study and training on top of a sound primary and secondary education. Professional organizations dedicated to supporting and encouraging women in these fields were created. Major existing professional organizations--like the AMA and the ABA--started paying attention to the issue, as well.
Today, you won't find many people defending the position that women are somehow less fit to be doctors or lawyers than men. That's gone. It took a long time, and it took a lot of people--mostly women--fighting a grueling and protracted battle against a broader community that was, at best, condescendingly tolerant of them, so long as their numbers were small enough and they accepted adapting themselves to life in a man's profession. You still see gender disparity, both in pay and people, and you still see a lot of the vestiges of the old system that need to be retooled, but there's been real progress.
Getting a solid number on how many women are employed as software engineers/programmers is tricky, but one recent effort compiled information from around 200 companies and found that about 15% of software engineers are women. Certainly not as bad as the medical and legal professions in 1970, but a far cry from what you'd expect--and, frankly, a far cry from where software engineering and programming has been in the past.
So here we are, in 2015. There's a lot to be done. We've barely even begun to accept that this is a problem yet, and the backlash against this concept is virulent, to put it lightly. That said, there's momentum building, and I'm hopeful that we're finally--finally--starting to move in the right direction.
The system won't be burned down, but the system won't survive in its current form, either. With any luck, 40 years from now, we'll be looking back on this with the same incredulity as we do on the legal and medical professions of yore.