I have backups that must be retained for 7 years to satisfy compliance requirements, but they are rarely if ever used for actual restores. DP can map a B2D device to Amazon S3 cloud storage, and that's great. But for long-term retention, I would like DP to migrate that S3 data to S3 IA (Infrequent Access) or ideally Glacier and still be able to see it, track it, and if necessary use it for restore. Or perhaps have DP write long-term data directly to S3 IA or Glacier via B2D device.
In this manner I can keep short-term backup data on S3 and push long-term archival data to less expensive Glacier storage, understanding of course the diminished service levels for Glacier compared to S3.