Ok, it is probably a little early to make this proclamation based on the growth of the usenet community around Microsoft.public groups, but the news of AOL no longer offering Usenet Access is a sign of things to come. The best post I've seen about this comes from Many 2 Many.
"This feels to me like they’re tearing down an old diner in a neighborhood I used to live in. I never go there anymore, but I spent 5 years of my life on usenet, and 2 of those years in a fever I can’t characterize as anything other than addiction. I learned to write there, and it’s one of only two places where I had people I’d call real friends who I never met IRL. (The other was Old Man Murray, RIP.)..."
"Still, it feels kind of funny. Usenet was such a spectacular experiment in the annals of human communication, the idea that it’s value isn’t worth the cost of keeping the servers running comes as a marker of things I already knew, but which still feel different when they become facts in the world. "
Personally I heard some of the Microsoft.public newsgroups most staunch supporters (our MVPs) really start foretelling the death of Usenet at the MVP summit this past year. The allure of modern web-forum based communities with moderation, improved identity, less spam, etc is starting to tear some of them away. Last year many of the developer newsgroups (and I'll lump developers into an early adopter category) actually saw a decrease in the number of return users. Look at the Asp.Net forum community. It already outpaces all of the public Asp.Net newsgroups. Sure, these are web guys, so they would naturally gravitate to the web interface. But how long is it before someone makes a great offline client that talks to standard web protocols to fit the bill of other high volume contributors whose only reason for not moving to web forums is the desire for the faster client cached access?