[indigochill]

People use Google because it's what they know and the alternatives for whatever reason do not sufficiently differentiate themselves in ways that the user cares about enough to switch.

In order to be disrupt Google, you don't make a better Google. You identify something Google doesn't deliver and which people care about enough to use your search engine. I don't think anyone knows right know what that hypothetical killer feature is, and most probably assume it doesn't exist.

On another level, though, incumbents have a habit of buying potential threats (which can be a pretty good deal when you're in venture capital land and need to show your shareholders high returns). Google's bought a number of companies with a different take on search over the years, such as Like.com and Clever Sense.