I hope once a Fediverse culture takes root we will see a second generation of federated services that start experimenting and doing things in ways that are, for lack of a better term, "natively" federated rather than simply trying to mimic something closed. That might be when it really takes off, when you start seeing things that work best in a federated environment and make awkward fits for a centralized one. A good example of something like this might be the mod scene in gaming, which Steam tries to get a piece of but can't quite seem to corner.
I found myself thinking a few days ago that half of threading on Twitter could be implemented with simple microblogging and a protocol for back-reference URLs (all of which can be done in something as simple as hugo or Jekyll) coupled with a standard for the user-agent to "unroll" the thread. This requires neither a centralized or federated service; it's built on basic web tech.
The only piece of the puzzle missing is that it only works one way; to see the whole 'conversation,' you'd need to find the tail of it (most recent comments). This sort of data-mashing is one of the things a centralized server can do simply and well (though it's certainly implementable on a federated service). But without a federated service, a rule for semantically identifying "topics" and web-crawler that knows how to sort by newest-to-oldest on a given topic identifier gives you the whole story.
[0] https://indieweb.org/reply [1] https://indieweb.org/Webmention
Not to imply Mastodon shouldn't exist... It is the beauty of the larger open-source ecosystem that in the absence of Mastodon, someone with a chip on their shoulder about Facebook and Twitter would write it. But the market is such that it will likely forever be an also-ran, and the irreducible complexity of hosting a service online is such that even if people use it, almost everyone will be trading one master for another when they leave Facebook for Mastodon, not becoming masters of their own fates.
Which is fine. We live in a society and all.