Upload & Sell: Off
The elephant in this room is what we are all afraid of and what will eventually have to happen. No more dedicated still photography (except for the traditionalist die-hards). Maybe similar to what has happened to film photography gradually over the years.
Nonsense. That was said about painting when photography came in. And about the "paperless office" when computers came in.
But at least still photography and painting have one thing in common. The image can be comprehended at a glance. Video consumes vast quantities of time, something ill-understood by those enamored of youtube tutorials and the like.
So there will always be a high demand for still photos, whether they are portraits on walls or illustrations on web pages.
If the means of production becomes efficient to shoot a couple of seconds (48-50 frames) of 4K video to extract a single frame, so be it. But I really don't think it is efficient:
Not even the photographer has time to sift through thousands of pictures to find the one good one. It is bad enough when photographing models and making 50 stills to choose three. Often, for a multitude of reasons, one needs to make 250 shots. Shooting video does not reduce the need because of things like posing and stray hair and expression and tight control of lighting as the model strikes poses.
So you would end up with 50 x 50 = 2500 or 50 x 250 = 12,500 frames to sift through.
Needles in a haystack. What a waste of time.
Yes, it will be useful for things like portrait photographers who have five (5) minutes to photograph a Very Important Person. So yes, they will shoot a ton of frames around each "shot" so they can be sure that the perfect expression is not ruined by a blink.
But expect Very Important People to insist on contracts that forbid video because they don't want or need high definition video floating around the world of them blowing their nose and other such indignities. If they can't relax a little while having their portrait made, they won't make great portraits.
Also, continuous lighting has many problems not associated with flash -- and some advantages.
So the outlook is a mixed bag and not a complete overthrow. But you can continue being afraid. I'm not.