If you'd like, I could start listing the breweries in my area who are doing quite well, making wonderful beer that's highly imaginative and top-quality, none of whom have had to sell out... If that list were expanded throughout the country, it would get rather long rather fast. I just visited Port Brewing/Lost Abbey last weekend, which is right down the street from a little place called Stone, maybe you've heard of it. PB/LA was packed to the gills with people and had every fermenter in the place running day and night.
In reality, we're in something of a Golden Age of craft beer. Never in history has there been better availability of high quality beer than there is now. I can drive down to the BevMo right now and take my pick from a selection of about 300 (or more) high quality craft beers. Woot!
The existence of The Big 3 is not doing as much damage as you think. Now, if you want to help the little guy, let's talk about getting rid of some of the silly regulations and laws than make it prohibitively expensive to start a micro-brewery. (Yes, I know the BMC guys lobby to keep those barriers up, but ultimately we vote for our lawmakers, and to be honest, this issue is something like #493,398,381 on a list of important issues for voters.)