Search has become a commodity in the eyes of most people who aren't power users. That is to say, as long as it works, one search engine is pretty much the same as the other.

If somebody is going to erode Google's hold on the market significantly, they are going to have to introduce entirely new features, or come up with a search that is orders-of-power better than Google. That is to say, the superiority has to be readily apparent to a human user and not just a slight improvement that can to be proven only by empirical testing.