If/when Threads ends up federating more fully with Mastodon, it likely still won't be on AP, and unless it opens up Instagram, it won't live on an open, accessible protocol—it'll just bridge to one.

Recognizing that Meta is turning the openness of the fediverse into a sales pitch (and, arguably, a bait-and-switch), we should resist taking its marketing at face value and uncritically repeating claims like, "When Threads federates, I can move it to Mastodon or merge it into my existing Mastodon account while keeping the connections I made there, as long as they have federated." We can't be sure that Threads will actually adhere to that norm.