For me at work, chat and videoconferencing have almost completely replaced email. Work email is just notifications and other automated crud for the most part, and little enough of that.

Mailing lists do seem mostly dead to me. For good reason.

I’m part of several mailing lists. They tend to have crummier formatting and be harder to share and discuss with others in other contexts since there’s no URL, or if there is, it takes work to dig it up (in whatever the archive is). The traffic also has mostly gone to almost zero as people have moved to Facebook groups.

Web forums seem livelier than ever, though. I run into forums everywhere with tech stuff. Mostly Discourse but also nodeBB and some custom stuff (Nim forums are written in Nim). Sometimes chat is bridged across all of Matrix/IRC/Gitter/Slack/Discourse. Most of these Just Work using GitHub or Google as my identity provider.

(Outside tech, there are a couple somewhat active shorthand email web forums and even a group blog - how’s that for a throwback? - that I know of.)