As the beer industry descended on Denver for the Great American Beer Festival, signs of the craft beer boom were all around.

In attendance were more than 630 breweries, the lucky ones able to quickly snag a spot before registration closed in just an hour and 40 minutes. Hundreds more breweries were on the wait list.

The brewers in Denver represented just a portion of the more than 2,500 breweries operating in the United States—the most since Prohibition. What's more, there are 1,500 other breweries in the planning stage.

With all the growth, many in the craft beer industry attending the festival frequently turned to the same question: How far can the craft boom go?

"I think at one point it will look like the restaurant industry, with a lot of small players entering and exiting," said Bart Watson, an economist with the Brewers Association. "That said, at this point, there is ... evidence that supply still isn't meeting demand."

(Read more: The booming beer brand trying to be the next Corona)

Take this: The Brewers Association reported mid-year 2013 growth of 15 percent in dollar sales and 13 percent in volume for craft beer. If these trends hold up, it will mark the fourth-straight year of double-digit growth.