And then the masses got onto the Internet. Lookup the term "Eternal September" [1]. The whole culture got overwhelmed by people that did not value the medium. Spam got out of hand, trolling was a most popular pastime. That killed Usenet, as normal discussion was impossible.

Can Usenet be revived? Not while there is money to be made on the Internet. Any attempt to gather people online gets perverted by someone smelling money.

Usenet was great until the mid-nineties.

[1] https://en.wikipedia.org/wiki/Eternal_September

These things are still there, I occasionally peak at newsgroups from time to time (there are free providers for the text trees) they're just not growing. IMO a lack of growth these days is probably a good thing.

It likely will. Give it some time for more internet screws to be tightened around the world. Once people see the screws had Loctite applied they will find more alternatives and revive older transports protocols. Usenet is still the vastly superior medium for automatically sharing massive amounts of multimedia content if one filters on pre-shared subjects preshared secrets, GPG signed messages. The spam can be entirely and automagically ignored.

My personal preference will always be anonymous Chroot SFTP and people using the LFTP client with the mirror subsystem and SFTP to split up batch jobs and individual files into multiple TCP streams. It works like rsync but much better as long as there are not massive numbers of nested sub-directories. LFTP+SFTP+mirror can easily max out any fiber connection but can also be rate limited with very granular controls. It's great for small circles of friends being significantly more secure and private. It's also super easy to automate uploads and downloads via cron. For even greater anonymity friends can build their own Tinc VPN mesh open source in a multi-star configuration so people do not see each others IP addresses. Internet bots don't even know what to do with anonymous chroot sftp and that's assuming I leave it on the default port.

For all their faults, big tech do mostly moderate their sites to the extent you won't find illegal things there.

Having multiple moderators of content, and multiple dimensions of moderation (think tags with attached scalar multipliers) could possibly work. Each host of the feed could then just not store anything that fails to pass as legal in their jurisdiction, or fails to meet their moderation policies.

Regardless of its arrangement, any large cooperative collection of stuff, albeit in a feed like usenet, or forums, or a files store, multidimensional ranking/moderating/reputation management is the way to go, IMHO.