From the article:
These references are almost definitely tied to the newly discovered "IoT Enterprise Subscription" edition of Windows 11, not the client version of Windows vNext.
With that said, I don't think it's unlikely that the next version of Windows will have some new capabilities that require a subscription to utilize, tied to your Microsoft account and services.
I came across this with a quick search. It looks pretty good!
Slskd is a modern client-server application for the Soulseek file-sharing network.