PAX South last year sure seemed to be at least 40/60, with a surprising number of good looking women who weren’t cosplay models even.
As to the OP, I think that in years past (I’m 43), there weren’t fewer nerds than now, but rather that it wasn’t nearly so socially acceptable among non-hardcore nerds to actually admit to it. So what you had was a big crowd of “in the closet” nerds who were dressing normally, acting normally, and circulating in the wider society, and you had a relatively small group of “hardcore” nerds who tended to be so socially awkward that they either didn’t know or didn’t care that their particular nerdery didn’t fit in with everyone else.
In college, there were girls in the sci-fi/gaming groups, but they tended to be equally awkward, so the hardcore nerds tended to be some combination of clueless, obsessive, and when they thought about girls, they got angry and misogynistic, as the only girls they knew were the awkward nerd girls… who despite being awkward and poorly groomed were always dating the “alpha” nerds, such as they were. The rest of the women around wanted nothing to do with them because they were smelly, obsessed about strange things, including what seemed to them to be animated Japanese tentacle porn and weird Japanese big-eyed sex fantasy women.
Now I don’t know how much of the stinky, obsessive, misogynistic nerd persona is due to misogynistic, stinky obsessive people being interested in nerdy stuff, or how much is due to the nerd lifestyle making people stinky, obsessive and misogynistic.
The rest of us, who were more interested in girls and socializing than being obsessive about watching anime or collating our Magic the Gathering cards, or playing D&D tended to be somewhat circumspect about our participation in the more nerdy activities, or were socially adept enough to own up to it, and not have people think we were nerds… because the last thing you wanted in say… 1992, was to be lumped in with the pungent, bearded weirdos who wore strange t-shirts and talked about role playing games and japanese animation.
I think what’s going on nowadays is that a lot of what would have been considered “nerdy” back in the day, is now cool, so the pool of today’s “nerds” is much larger and encompasses a lot of people who would have kept their nerdity in the closet in prior eras.
But I’d bet the core of awkward, stinky, obsessive nerds is still there, even if they’re outnumbered (and probably just as shunned) by the rest of the more normal latter-day nerds.
(FYI… basing my observations on 20 some-odd years of being a closeted nerd, and interacting with the un-closeted ones in college (1991-1996) as a RA in the honors dorm, and thereby knowing a lot of people in the sci-fi and gaming clubs.)