The #fediverse is one of the most hopeful aspects of the internet, since it tries to bring it back to its decentralized, federated roots. In my opinion, there is no other way to guarantee free communication.
However, it is not without its challenges. Looking ahead, it's easy to identify some of them:
1. Centralization is an emergent phenomenon. We can see this happening with the distribution of instance sizes, and the clear “rich get richer” dynamics that take place. This is not due to bad actors, it is simply how people tend to behave.
2. Commercialization is yet to hit this platform, but if it becomes popular, it will undoubtedly happen. Instances that serve ads, promote content, etc, will appear at some point.
3. Related to point 2, it is possible that Google and/or Microsoft will seize the opportunity to try once more to move into the social media domain, and make services that connect to the #fediverse. This will be sold as an adoption of the federation, and hence progress. But to see how that goes, we need only to remember what happened with google chat and the open Jabber protocol — they abandoned it as soon as their service became popular enough. Bait and switch.
4. Legal intimidation of smaller instances is a real menace. The push to force Facebook/Twitter/etc to be liable for what users post will backfire, and render every instance admin responsible for what every single user posts. Note that it does not matter one bit if the content is actually problematic — a single cease and desist letter from a lawyer will terrify most admins out there.
These are not problems without solution, but it's unclear how things will unfold.




