GoogleDrive, DropBox etc does not offer the same sort of functionality the OneDrive offers for “App Storage”. For the first release it will just be for DropBox.
But so your aware of the future plans for Asset Cat. If this hits off and people actually like it. I plan to rebuild it without Unity, making a full featured desktop application with loads more functionality. Hosting in the cloud would be an optional feature and if so, done on one dedicated server. So no need for having an account choosing between DropBox, Google etc
Thanks for you feedback :)