This is like nuclear war vs. guerilla warfare. It's awfully hard, maybe impossible, to be good at both. The Afghans would be crazy to engage the U.S. in nuclear war, but no one knows their caves like they do. Same thing in search. How could Google possibly know all the nuances of 30,000 different industries? There's plenty of business for everyone. The guerillas will just have to choose their niche; that's about the only way they can compete now.
You're right Google can't know the nuances of every business, but exactly because they are so good at generic search, they can leverage their technology to deliver better results in niches too.
Here is an example: MSDN library search versus Google site search on MSDN library site. Google is better, presumably because they take into account all external sites linking to MSDN. Never mind they don't know specifics about site format or contents.
