1st: Stone rocks. Period.
2nd: I agree that some markets are saturated, while others aren't. I also feel that there are many untapped markets in the US, but they are untapped for good reason. Texas is a great example. Sure, there are texans that really want more craft beer, but they are the 1%. 99% of people in Texas want BMC or Shiner.
3nd: There are a lot of breweries out there that aren't going to make it. Their beer isn't that good, and they don't bring anything new or interesting to their market. I don't see a huge 'bubble' popping, but as the market gets more and more saturated, it's going to be much harder for the crappy to mediocre breweries to grind out a profit. Expect to see the boom continue for another two years ago. You'll see a leveling off, then you'll see a metric crapton of 3-15bbl breweries for sale.
Any brewery making excellent beer with an owner that has some business sense will be just fine. There are so many breweries pumping out mediocre beer right now. The great breweries won't have any issue rising above them when the bubble pops.
And one small rant: New breweries that just started bottling: Put a GD bottling date on your beers. No, i'm not going to buy a $7 bomber of your IPA if A. I've never heard of your brewery before, and B. I have no idea how long it's been sitting on the shelf. I'm looking at you Knee Deep Brewing and your $11/bomber Simtra Triple IPA. /rant