I don't like the clickbait title at all -- Mastodon's clearly going to survive, at least for the forseeable future, and it wouldn't surprise me if it outlives Xitter.
Still, Mastodon is struggling; most of the people who checkd it out in the November 2022 surge (or the smaller June 2023 surge) didn't stick around, and numbers have been steadily declining for the last year. The author makes some good points, and some of the comments are excellent.
Mastodon has a larger percentage of the fediverse audience than any other agent, so not sure how you can equate that to struggling to survive. It is somewhat polluted with former Twatter left wing retards but that is just because it's resemblance to Twatter lead to it's adoption by a lot of former twatter twits when Musk took Twatter over.
Fwiw, a lot of people here call it Xhitter. Bc it sounds like Shitter, which is what the site has become (I wouldn't know personally, I didn't have an account there even before the Musk took it over:-).