Comment by BeetleB

Mastodon has more users than HN. It's a success. It's also unlikely to go away. Well, OK, it may go away if BlueSky ever becomes decentralized in practice. If that doesn't happen, the only "threat" to Mastodon is some other federated, decentralized service.

It's been around long enough that it has reached steady state. Existing (active) users are happy with its architecture, and are not concerned with discoverability, etc. Why would they leave?