No search isn't a Natural Monopoly. There isn't some sole magical search spring that Google taps into or a need to dig search lines beneath everybody's houses like a utility. "It is very useful" does not make something a utility - having exclusivity to a commons is what makes it so.
There is nothing exclusive about search - Firefox and many other browsers allow you to choose between multiple search engines at any time without setting a permanent default.
There is nothing exclusive about search - Firefox and many other browsers allow you to choose between multiple search engines at any time without setting a permanent default.