Dropbox is indeed stopping the V1 API on September 28, 2017 which will mean that any version of Out-of-the-Box before version 1.8 will stop working on that date.
- To keep using the plugin, download the latest Out-of-the-Box package
NOTICE: Please note that plugin requirements are changed and that you will need PHP version 5.5 or higher. I understand that this can be an issue, but this is a change I have to make to be able to use the new Dropbox API library. All other settings and shortcodes will just keep working!