This statement is rather questionable: "Humans, along with most other animals, will go extinct before the end of this century."
While I'd read more to see their reasoning, I'd doubt even endangered is a stretch within 2100. Unless they predict an event like meteor strike, there are well adapted communities living off in remote, extreme conditions with very little reliance on modern civilization. Even in a wide collapse of our soceity, many of them might still still scrape by.