Dropbox announced earlier in the year that they would be deprecating the Sync and Datastore APIs in October. That deadline is fast approaching.
What does it mean for apps utilizing Ensembles? If you are still using the Sync API, best to move over to the Core API. Users should not experience any major impact, other than perhaps an additional login. The files stored by Ensembles remain in the same locations.
Dropbox have also announced that you need to make minor changes to your app support iOS 9. These changes cannot be made inside of Ensembles — you have to edit the app's Info.plist file. Details are provided here.