This is of interest to me as well. Also I would like to add the ability of not only hosting content (images, videos, documents, etc) for traditional infrastructure like you mentioned, but also for other open internet services on IC as well.
For example, if users upload short videos to CanCan, they may also prefer to upload the same clips to say, a future OpenInsta, OpenFB, OpenYoutube, etc. In such a case, wouldn’t it be better to host the content on such “user owned content only cannisters” for the specific purpose of storage that can then be used across multiple services, than say in a CanCan canister in this example? The latter would also result in extra cycles being burnt by CanCan rather than the other services that may use them, which won’t be very fair for the makers of one (CanCan in this case) over the others.