Sudden change is called an extinction event. Think of the dinosaurs. 65 million years ago, they were everywhere, these lumbering beasts that ruled the land, the sea, and even the air. 64,199,000 years ago (give or take), all we had left were some lizards, some little birds, and a few gators, their cousins. There was nothing gradual or gentle about the end of the dinosaurs at all. They were here, and then an asteroid* smacked into the earth, and then they were gone. Just like that.
Extinction events aren't that common, but when they occur, they're scary and exciting, all at once. They're unrelenting. And nothing is the same after the event. Nothing.
Social Media is an asteroid. It has struck the earth. 20th-Century businesses... those are the dinosaurs of our time. And their time has come.