Is there a way to modify the storage backend used by a Django FileField?

Question

I am saving some uploaded files with a Django FileField set to use DefaultStorage backend. At some point after the file has been uploaded I'd like to move them to a different storage backend i.e. change the FileField's storage attribute (obv. after saving the contents of the source file to the new storage location). Simply changing the FileField instances storage doesn't seem to work.

Is this possible without the use of a second FileField model attr which has been told to use a different storage backend? Ideally I'd like to not have to double up on the fields and put switches in all the templates that reference the files.

Thanks!