IMO, Flash died because it didn't play nice with the conventions of the web. There were workarounds, but generally it broke all of the things HTML could do, like being searchable & selectable, navigable with a keyboard, built of code you could inspect, addressable with a direct link, even working with the browser's back button.
The actual animations and (sometimes) beautiful interfaces were not the problem. People generally loved that.
Generally there's no need for a new product in this space because CSS does everything Flash once did, but adheres to web conventions.
There probably is an opportunity, though. I'm not a motion graphics person - does Adobe Animate fit the bill at all? What do you think is missing today that we once had with Flash?