So why would any company have any interest in shutting down legal sharing? Has there been any evidence that any media company has tried to shut down any legal sharing service that is only used for legal file sharing? It would seem you're implying that.
Technology for sharing data does not care what data gets shared and has no way of doing so. Positing that nobody would shut down a service that is only used for legal sharing is therefore a fairly pointless exercise. Especially since definitions of legality vary so widely.
