Whether shorts will replace still or not I don't know. There is a pull to add more frames because many, probably most photos, don't tell enough of a story.
One of the biggest challenges we have in still photography is telling a story in a single shot; putting/showing a subject in an interesting situation.
A form that I've experimented with just a little bit is creating a contact sheet from a single roll of film that tells a larger story. It's a way to add more context points from a single "event" into a single print. Could be a Norman Rockwell kind of idea (but not form) or maybe a still version of the movie clip idea, maybe its a printed version of the slide shows we/I enjoyed way back when.
Whatever the drive, there is a pull to add more frames because IMO many, probably most photos, don't tell enough of a story by themselves.