This has come up a fair few times in our company, we use O365 in conjunction with OneDrive and sometimes the Onedrive/SharePoint autosave doesn't actually save changes/create a new version.

It would be great if a snapshot copy of all presentations could be kept locally on close if the user didn't save it (a confirmed valid save).

This would also help us with people working for ages on something and accidentally closing it without saving and thus losing all their work. The snapshots could be cleared out daily/weekly as set by the user/group policy.

This would provide users a place to recover work they'd forgotten to save, help when the autosave/live editing part of O365 is not syncing or behind on sync as well.

The current recover unsaved documents option is ok but rarely shows anything for our workers - especially if the thing they are working on happens to be editing a previously saved presentation that sits on sharepoint or on OneDrive.