If you have a Mastodon account, you don’t need to sign up for Threads. You will be able to directly interact with Threads posts and users soon enough.
when they flip the switch on joining the Fediverse, it can become an “Eternal September” type of situation for other Fediverse servers, like when AOL joined millions of people to the Usenet network in 1993.
Meta will have to learn how to segregate their advertising and data retention interests away from other Fediverse servers. Numerous Fediverse servers have preemptively defederated from Threads in advance out of fears over these interests.
Meta will also have to learn how to play nice with other Fediverse servers when it comes to data migration between servers. Otherwise they can find themselves locked out through defederation.
If you wanted the idea of “microblogging social media as a public, distributed utility like email” to go mainstream, something like Threads may be the first well-funded foray into that idea. No turning back now.
If you wanted to no longer have to be locked out from your friends and content because the social media app du jour doesn’t work well anymore/doesn’t play nice with other apps, watch this space.
