I don't recall Drew ever calling it a GDrive killer, in the couple conversations I had with him about Dropbox. And, GDrive was a hypothetical product at the time, and still mostly a hypothetical product today. I'm guessing they were probably considering the impact a Google competitor would have on their product, just like they probably considered the impact Apple, Microsoft, and others would have. But, I don't think they were designing based on what they thought the big guys would make.