quick simple stock header image for quick posts (like Secret's)
annotation on images, a note, a link to people, product, story,...
Amazon product link, or other 3rd party store front link.
unlisted stories, not visible anywhere unless from the shared link (like this story, I don't want it show up on my personal stories... If you are reading this you know what I mean!)
allow embed custom analytics code, eg GA, or Facebook ad tracking code
follow up stories feature, users can response to story and create new stories. This was popular in blogs in old day. It can be used for series long blog posts, or QA style follow up, or a topic based story contest
future publish, allow set a time to publish the story or include it in a collection