The state of the mystery (and thriller, I suppose) is interesting right now.
For one thing, women rule. According to a poll done by Bowker at the behest of Sisters in Crime, the vast majority of people who identify themselves as mystery readers -- almost 70 percent -- are female. This marks one of the most profound branding shifts of recent times. On a par with turning Las Vegas into a family destination, only successful.
In the so-called Golden Age of the mystery (I'd actually argue that we're in the Golden Age right now), women wrote and purchased a very substantial share of mystery novels. Christie, Marsh, Sayers, Tey, and many others were murder generators of the first rank, turning out one dependable book after another.
These were mostly what we call cozies these days. Little blood was spilled on the page, murder weapons were often exotic, and suspects and victims alike were often upper class. These were the books in which, as Raymond Chandler said, the suspects "sit sipping Singapore slings and sneering at each other while the flat-feet crawl to and fro under the Persian rugs, with their bowler hats on."
But then, out of the pulps, a school of male American writers arose to develop the elements of a style that we call hard-boiled. The leading revolutionary was Dashiell Hammett who, as Chandler said, "Gave murder back to the kind of people who commit it." Gradually, the hard-boiled school took over a goodly chunk of the market, and by the time of Mickey Spillane in the fifties, the testosterone content of the mystery best-seller list was through the roof.
Now, though, fifty years after Spillane, women write, and read, most of the mysteries sold and bought. And some of them are more hard-boiled than Spillane ever was. It's a good thing for Leighton, Dan, Stan, Michael, Jeffrey, and me that women are statistically much more likely to read male writers than males are to read females. If it weren't for this open-mindedness, we'd all be writing catalog copy for LL Bean.
So we don't have to worry, we male writers, about that. What we do have to worry about -- male and female alike -- is that mystery readers are getting older, as the Bowker survey demonstrates with doleful precision. (The survey isn't broad enough to reflect what I suspect is the truth, which is that the reading public for all books is getting older.)
On the other hand, just as it looks at though most mysteries will be purchased with funds hoarded from Social Security, along comes the e-book: cheaper and much more appealing to the young. As the mainstream publishers bite their nails and lay in extra supplies of red ink, the most democratic form of publishing in the history of the world springs into being.
What that means is that anyone can write and publish a mystery now, even a man. There will be a lot of junk put online -- the mainstream publishers at least established some minimum threshold of quality -- but I believe some kind of sifting mechanism will arise to pluck the nuggets from the sludge.