Honest question, how would usenet get killed?
Usenet posts are, for all intents and purposes, anonymous. Sure there's some source header information, but that's extremely easy to spoof and there's already dozens of SAAS upload services which hide the user's identity.
Downloaders are as anonymous as their NNTP provider makes them, thanks to SSL encrypted connections.
The only attack vector for copyright holders is to go after the service providers, which _should_ fall under safe-haven rules. The worst they can do is issue DMCA takedowns for individual posts, which can number in the hundred of thousands for just a single video.
If safe haven didn't apply, usenet itself is distributed, take down one host and people will simply move to another.