“This is really going to impact institutions that we take for granted,” Internet Archive director of archiving and data services Jefferson Bailey told the Standard, “like our museums, our historical societies, our public libraries, our academic libraries — just a lot of people that keep information free and accessible and online.”
I made forum posts going as far back as 2000. Almost all of them are gone forever due to the reasons you mentioned. Even the wayback machine might have a snapshot of the forum, but not the threads made them, and not the posts made within those threads.
I’m wondering if any BBS posts I made way, way back when are on any drives anywhere. I’m sure it’s possible. I’m pretty sure the USENET posts I made back in the day started to get archived by Google (at least) and I’m pretty they will be around for quite some time.
Proprietary things built and run by private tyrannies using no standard protocol (like NNTP or ActivityPub) I don’t give much of a chance…