people will move to the next social media site (or jump to another medium if it's good enough) even before Twitter shuts down.
This happens all the time and there are parallels with other format / medium shifts (Gutenberg invents movable type, newspapers supplanted by news reels at the cinema -> people buy radio receivers -> broadcast television -> cable news -> whatever we have today with our always-on internet connections and services.
My main point here is that audiences are fluid, we can respect their intelligence, and they go where the content is.
