Okay, so right now government agencies, schools, and small business often use Facebook or Twitter for their web presence rather than start their own websites. For a few days there, while Twitter had the login-wall up and was rate-limiting, we had some serious problems wtih Amber Alerts, weather notices, safety notices and other announcements from US government entities. It looked like the government would be forced to start hiring web admins and setting up RSS Feeds and Mastodon servers to get the word out.
But now Threads is here, and they can just as easily as they were on Twitter outsource their web presence for free. They can just make Threads accounts for these public safety and security announcements.
Schools and small businesses can do the same thing, have instantly better reach than on Mastodon, and never have to worry about ActivityPub at all. All of these people remain in the Metagarden, and worst of all, we're forced to federate to them because public safety info is there.
This will significantly slow the growth of the Fediverse.
Now, a lot of stuff has gone to pasture or become rare because of EEE... forums, personal blogs, IRC and stuff. But Linux is still going strong. So maybe there's enough of us counterculture sorts to keep the Fediverse active and independent. But even so, Threads can very easily kill any growth beyond that AND force us to federate or at least have alternate accounts to view these necessary services.
I do not have a solution, but I think this is an aspect of the problem that hasn't been focused on. We talk about mass defederation to save ourselves and list all these frivolous things like celebrities and journalist twitters (while assuming we have the full news feed) without taking the incredibly important government-run accounts into the conversation. Because defederating from the account that posts Amber Alerts is not a simple choice.
And one of the things that got people back in the day with BBSes, IRCs, forums...etc.. was that they were in school and that was the computer culture at school. Now the computer culture at school is Facebook, and will be Threads. All we have to offer is an ad-free experience, and a knowledge/cost curve to any institutions that are choosing between running their own server and just endorsing the use of Meta's products. This will slow down growth. It may well stop it.