> Thought experiment: what could that disruptive niche be?
Someone needs to write/buy a search engine and then build a really rich API into the internals of it that lets 3rd parties write customized search engines. How about an auto parts search engine, or a search engine for spanish-speaking people living in southern california? What about a Christian search engine, or a meme search engine?
When someone can empower 3rd party developers to make the same kinds of decisions as Google does, but with different tradeoffs, and they really put the full institution behind supporting that, I think:
A) Google will have a hard time competing because they won't be able to give the personal attention to the needs of what is, effectively, a community of modmakers.
B) This new company will capture the long tail of search. Only a sliver of that is covered right now, with a scattering of niche search engines (Google Scholar, etc).
C) The number of users could be VERY large. It could be the cable to Google's broadcast television.
D) Getting started wouldn't require any massive technological achievements. Just find an underserved niche where even a really really stupid search engine would work better than Google. Write it, figure out how to make money off it it, grow. Start with something that requires only a small index. Slowly expand into additional niches according to what will help keep the company and the tech moving forward.
Google's bet is that any information you can glean from someone coming to a niche search engine can be reasonably approximated with contextual information in the query. That's proved true for many queries, but the key is to find the queries where it's really not.