I think the reason you don't see Beretta 92's on the shelves anymore is they've interrupted production and moved their plant from Maryland to Tennessee. I also think the lack of popularity of the SIG P-Series guns has more to do with the inconsistent quality control at SIG rather than a dislike for the inherent design of their pistols.
Beretta has a bunch of new options rolling out in their 92 Series guns that address some of the knocks against them (can't do anything for those that don't care for DA/SA, though). Expect to see the Vertec/M9A3 slide become more common in the line-up as it allows a front dovetail and replaceable front sights without having to use the Brigadier slide. Expect to see an increasing number of decocker only models, or at least the option to user switch the gun from safety/decocker to decocker only.
The DA/SA guns are the flagship guns in the Tanfoglio and an CZ line-ups, and while these aren't real large selling makes, they do sell a lot of guns to competition shooters, and these guns win a lot. As long as people copy what the top competition shooters are using, and a lot of them are shooting these guns, the DA/SA guns will be around.
Every time I watch this Ernest Langdon Beretta 92/M9 video, I want to buy a Beretta 92.
It doesn't get any better than (about 2:05 - 2:45), "It's not like a Glock..."