In the beginning there was Best of the Web, then Yahoo!, then Google. What's next? What would it take to topple Google's hegemony of the web?
Google would be a hard takedown, but they still have a lot of room for improvement with their search results, so there is some scope for another company to do it all better. I think the future of search will lie with advanced artificial intelligence routines that can view, and react to, a web page in a similar fashion to a human. With computer technology and AI routines improving all the time, it's possible that this may become viable within the next 5-10 years.