If we're absolutely sure that we'll never have to do a listing of previews associated to a piece of content, than I think the CF can go. /cc @nicolaasmatthijs @bp323 

It's also used to verify if the filename that the user passed in the link /api/content/<id>/previews/<filename>?signature=...&expires=.. actually exists. I don't think it would be a major issue if that check goes away, as nginx would just return 404.