The source code of Google Docs files has many messages related to "Google Drive", but all of them have one thing in common: they replace similar messages that include "Documents List". Here are two examples: "items haved been removed from your Documents List" / "items haved been removed from your Google Drive", "Add to my Documents List" / "Add to My Google Drive".
This suggests that Google Drive could be the new name of the Google Docs List, while Google Docs could be detached from the file storage interface and only be an online office suite. Google Docs is not the right name for an online storage application that lets you upload not just documents, but also music, videos, archives, photos and other files. Hopefully, the rebranding will bring more free storage, file syncing apps for mobile and desktop and integration with third-party apps.
Steven Levy's "In the Plex" included an interesting story about Google Drive being superseded by Google Docs because "files are so 1990". Google's Sundar Pichai said that "when people use our Google Docs, there are no more files. You just start editing in the cloud, and there's never a file." Google Drive might be a better name for a service that stores user files, whether they're created using Web apps, mobile apps or desktop apps.