As long as the data that is made is independent of a domain, it’s not centralised and can flow and be accessible anywhere. When data is only accessible from single point, it is centralised. Web5 DWNs can also be considered “centralised” if everyone use a single central cloud provider, but both protocols support any number of relays/DWNs pr user.
There is no chance that Nostr and DWN is going the way of Telegram/Samorai.