Fashions
Hard to predict. These things ebb and flow with gunrag articles sometimes.
Usually closely follows something new and deadly-lookin'...but classic designs never really leave us...or at least not for very long. They may be shuffled to the back of the shelf for a time, but they always seem to re-emerge, ready and willing to take up where they left off.
Some examples that just don't seem to go away are:
The 1911 (of course) Nearly a hundred and still sellin'...and stirring up flame wars on internet forums.
The '98 Mauser.
The M-94 Winchester rifle. 112 years young and still here. Marlin leverguns too. Same concept. Same 19th century technology. Still hangin' in there.
The single-action revolver...notably the '73 SAA and the Bisley.
The double-action revolver. They just keep sellin' and sellin' and sellin'
in the face of 15 and 20-round semi-autos...and they're being carried for
serious purposes every day by thousands of people who understand the nature of a gunfight.
The pump/slide-action shotgun...in spite of all the killer-diller, uber-tactical semi-autos that have a "firepower" edge, whatever that means.
The double shotgun...even the exposed hammer models are regaining a spot in the market, and not just because of Cowboy Action. They're simple and practical.
The Browning P-35. The original hi-cap "Wondernine" has a faithful following for a very good reason. It's a damn good pistol.
The .22 pump rifle. Really now...Does it get any better than this on a lazy Sunday afternoon?