NEW ORLEANS – At this week’s annual meeting of the National Beer Wholesalers Association in New Orleans, one issue kept foaming up: Americans, especially the much-desired Millennials, aren't drinking enough beer these days.

Although the meeting made clear that the industry is still very profitable, the recent sales volume slide is taking on a new sense of urgency, according to an article in Ad Age.

The concern from some in the industry is that once these younger drinkers are “lost” as customers, it will be very hard to get them back.  According to the Ad Age article, total beer volume is on pace to decline 1% in 2014, and Anheuser-Busch InBev and MillerCoors will both be down, according to some estimates. That would follow shipment declines in four of the past five years, according to figures from Beer Marketer's Insights.

The underlying factors in 2014 are the same ones that have plagued big brands in recent years: Wine and spirits continue to make gains. And while craft beer brands are surging, the gains are not enough to overcome declining sales of stalwarts like Budweiser, Bud Light, Miller Lite and Coors Light.

One theory behind the decline particularly of “legacy” brewers is that the big light beer brands that launched in the early 1980s are in a freefall simply because the current generation of drinkers does not want to drink what the generation before it drank, a facet of the so-called "product life cycle theory," which holds that big brands will eventually mature and begin to falter. Others, however, largely reject this theory, instead saying recent declines are due to external factors such as stubbornly high jobless rates — especially among young adult males.

But brewing executives expressed faith in their big brands, which they are seeking to fix with marketing, packaging and other changes. But if big brands are going to make a comeback, it could depend on some factors outside of the control of marketers — like the economy.