Allow redirected folders to be stored in a separate container
Allow redirected folders (Desktop, Downloads, Documents, etc) to be stored in a separate container that way the profile can be "reset" or deleted without loss of data. This would also hybrid on-prem/azure environments easier as you could leverage cloud cache for folder redirection as well.
Allowing multiple containers, and storing information outside of the profile will likely be implemented separately from each other. These two items are being used to track relative prioritization.
It seems like this is just one scope of what could be done with the custom data containers that currently has the most votes for FSLogix features.