Just like there’s Lemmy and Kbin that powers the “threadiverse” / reddit-like portion of the fediverse, Mastodon is only one software that enables micro-blogging like experiences. There’s Pleroma, Misskey and many more. And of course there’s always the possibility for more to be developed over time.
Of Mastodon there’s likely hundreds of so-called “forks” out there. Since it is open source, people can take that source code, and host their own version of the project. This means they can make their own changes, include changes by others, remove features they don’t like, and so on.
Mastodon is not just run by a handful of people owned by a corporation, forced to work for them. Large parts of the project are contributed by volunteers, which can jump ship to another implementation as soon as they feel like the one they’ve contributed to is not acting in the interest of users.
Admins which actually host Mastodon instances get to decide when to update to a newer version, or whether they want to use a fork that includes the features they like (which the “official” Mastodon project has not (yet) included) or anti-features that might’ve been put there due to pressure from outside (possible but less likely).
The power here is in the hands of users and admins. We just have to be careful not to let a company like Google or Facebook/Meta take control over a substantial portion of the fediverse. See also: How to Kill a Decentralised Network (such as the Fediverse)