@johncarlosbaez @Gargron tl;dr. You interop as long as it take to create enough connections between your walled garden and the fediverse. Then you shut the interop down, breaking all these connections, causing fedi users to migrate into your walled garden.
That's what Meta (and Google) did to XMPP.
Why? Because they are here to generate profit for their shareholders, and for nothing else.
@dimpase You will only lose what you never actually had 
@dimpase Everyone who says what you don't like is a troll, surely 
@dimpase I only said what I said. The rest you did on your own.
In case it needs to be explained, I'm not saying that Facebook is suddenly going to be a good boy, but the people lost were not “here” in the first place. They already come and go, right now.
And XMPP never died. Masses didn't care, but it certainly exists and many people use it daily.
@tennoseremel @johncarlosbaez @Gargron
You forget that Mastodon is first of all, user-counts wise, is the place where came to escape Twitter.
Once Meta does the user heist, Mastodon will be left without e.g. news media, services (hey, how about e.g. a national police force of Finland?) will become unavailable for Mastodon users, etc., as these out of necessity, by nature of why they are here in the first place, will be out of here by now.
Why are you advocating for a Meta-run version of Twitter?
@dimpase You are mistaken. People were here before it was popular to leave Twitter.
As for news media and services, they are just a noise on a social media platform. For news there is RSS, for “national police force,” I'm not even sure I need their presence TBH.
@johncarlosbaez If those people don't really care about being free from corporate abuse and run to that side at the first call, I'm not going to stop them. Big numbers are not a virtue by itself.
@johncarlosbaez Not to mention that these people are already here without Threads federating. Why would they leave, if Threads turn federation on and off later?
Those that will come after Threads fully federating might leave if they will turn it off, but, as I said, you will lose what you never really had – people who were not interested in the Fediverse, but only “because Facebook.” Although in this case they are more likely to join threads directly.