At the Extend phase I would encourage fighting back - or at least making it clear that we are separate from Threads and shouldn't copy them.
I wouldn't leave for Threads during Extinguish; I'd stay here. But I would just sit back and mourn what could've been.
Just like how I mourn XMPP whenever I see Pidgin in software center.
Just like how I mourn when my Windows Phone had SMS, Hangouts, and Facebook Messenger all in the stock texting app.
I'll survive. I'm not going to Zuck's site. But I'll be really sad that I'm not going to be able to talk to my friends from anywhere else.
This thread is specific to Kbin, which is why I mention it.
Lemmy doesn't integrate well with the rest of the fediverse at all, period. It's one of the many reasons why I left.
Threads users won't be able to make articles here on Kbin anyway (IIRC); they'd make microblogs. So blocking them would effectively remove them from your microblogs, and if they reply to anything in here I don't think you'll see that either.