I can believe that if there were another solution that were marginally better it might not be enough to unseat the top player in the market. But switching costs in search are extremely low so it would be surprising if people did not switch for a substantially better experience. In particular, it would require us to believe that what happened when Google showed up on the scene would not happen again, and to me that just does not seem likely.
Perhaps switching costs are low, but they're certainly higher than people are willing to pay in many cases. Switching costs as high as "changing the default search provider" are demonstrably prohibitive.
