Banning bitcointalk is not affecting the Bitcoin network in any way. Sure, it's the digital museum of Bitcoin, but enthusiasts can already migrate elsewhere.

Decentralizing a forum is not proved sustainable. Scaling is a nightmare, works more complexly, moderation is minimum if not zero (which is pretty much the same as here), and will probably incentivize users to use a third party. I have used nostr, which is a decentralized social network like Twitter, and it's even worse than Twitter.

And BTW, bitcointalk is not scheduled to be banned.