If Google's goal is to provide us with a distributed storage mechanism, then a better strategy would be to provide a better interface to their web offerings on existing operating systems.
No matter how much we desire a web-centric user experience, there will always be a need for software that takes advantage of all the computing power available in as small a foot print that is right in front of you. The question is will Google's OS provide this ability equally as well as Windows or Mac OSX can in order to be considered a "complete" operating system that has additional advantages.