The first wave was people with left wing identities who were tired of being harassed on mainstream platforms like Twitter.
The second wave was Japanese lolicon enthusiasts (without diving too deep down this rabbit hole, lolicon is a popular but weird and nerdy thing to be into in Japan).
The third wave was sex workers in response to SESTA/FOSTA eliminating platforms they used in the past.
All these waves set up their own instances, and they don't communicate much with the other waves.
If you look at what these waves all have in common (aside from using the software), there's just one thing. They were all posting stuff that didn't fit in on a mainstream platform. In the first case it was due to harassment, in the second it was embarrassment, in the third it was legality.
The users are already bifurcating the network, admins routinely share blocklists of sites that they don't want included in their version of the fediverse. Being able to block instances and people you don't like is one of Mastodon's killer features.
I don't think it will become the next outrage machine, people will just block and bifurcate. I do think users will keep setting up Mastodon instances in waves similar to the first three. I'd be surprised if Mastodon ever powered a better version of the commons we currently have on FB, Twitter etc. [1] The feature Mastodon added to federation (and that made it more popular than similar software) is the ability to not federate with people who are different from you.
[1] The "fediverse" at large has some potential to do this if it receives mass adoption. Think of a scenario like WordPress integrating federation features into the Core. This would bring federation to the mainstream.
[cw: food] I ate a burrito
I've since disabled content warnings, because I think it gets in the way.. But then it fails the second and third waves, because they post childporn and sex ads..
So I've ended up blocking pawoo.net and switter.at
Which is kinda the problem on mastodon, there's nothing in between silly content warnings written by people that are offended by the slightest thing, and content warnings for childporn drawings
Perhaps they'd need to implement a summary tag or something, so that people can configure their clients to only show the summaries for those who want to, and allows you to always expand them and still hide everything behind a CW.
Unless everyone is running instances on their mobile phones using a giant global mesh, it is perfectly within the capabilities of modern nation states to shutdown these networks.