Yes. It is approaching critical mass and will plateau. This is common in any industry or retail sector. There are only so many consumers, with a determinate amount of spendable dollar, in any given area.
Beyond that, a business has to diversify with the trends. In brewing, during the current fad and phase, the only way make money is grossly over-hop the hell out of everything. If you plan on making only or mostly high quality and to-style beers, you will fall flat on your face.
The typical status quo beer drinker is not going to pay $8 per pint for a very good pale ale or kolsch. They will buy a 6 pack of bud lite or coors light for the same price and say "it's the same thing". There is only a small sector of the population that brews or even understands the difference between good and bad, and typically a home brewer that has enough batches under his belt to kick out some great beer, won't patronize a brew pub as much as billy-bob-the-hipster that can't even make ice or oatmeal at home.