A lot of people are leaving, but I don't think this is directly a symptom of it dying.

Just because someone is highly followed and well known doesn't necessarily mean they have to post a lot. I mean, all of the people with the most followers are celebrities who are extremely well known, or ex-presidents, so it makes sense they would have a lot of followers.

I'm not really super convinced follower count is super closely tied to the amount of content posted. You could have a lot of people who followed Barrack Obama just because he's the ex president, and they didn't really think about it much more than that, and don't pay a whole lot of attention when it comes to politics.

I definitely acknowledge that people are leaving Twitter and the culture of Twitter is totally dead, though.