I'm a lot more sanguine about communities muting someone because they don't like that person than about companies muting someone because it's profitable to do so.
You can hypothesize a future in which Mastodon gets very popular, and in which a single for-profit node or a coordinated group of such nodes monopolize it and end up wielding censorship power similar to traditional centralized social media sites, but that's not what it's designed to do and there's no reason to assume it's a fait accompli.
All I really want from a social network is to be able to share small files with my friends and see small files that my friends have shared with me. It's convenient to have a for-profit handle all the hard parts (checking whether people are who say they are, storing the stuff when one of us is offline, etc) but it's not an actual requirement. Especially if some portion of the members of the network have a $5 VPS, which is certain to be true.
(As an aside, it mystifies me that some VPS provider hasn't already built this. A FOSS decentralized social network that requires a small dedicated server would be like a whalefall for that industry. If I were a PM at Amazon, I would have a team contributing 'store my files on AWS instead of my phone' to Scuttlebutt right now, and ditto for every other promising-looking decentralized social app.)
You can hypothesize a future in which Mastodon gets very popular, and in which a single for-profit node or a coordinated group of such nodes monopolize it and end up wielding censorship power similar to traditional centralized social media sites, but that's not what it's designed to do and there's no reason to assume it's a fait accompli.