Another intriguing post from Robin Sloan:
https://www.robinsloan.com/lab/specifying-spring-83/
My own approach has been to keep the timeline format and use a ranking algorithm to handle the disparity between people who post a lot and those who post a little. I've been thinking a bit lately about dialing the algorithm a bit more over to the "infrequent posters" side. There is a trade-off between doing that and keeping the timeline fresh, though. e.g. if someone posts a Big Important Announcement, it'd be nice to make sure you at least see the subject line.
My other main thought is "can this be done without introducing a new protocol?" e.g. maybe Yakread could let you create a page(s) with your collection of boards. Except the boards could just be regular newsletters/feeds/social media accounts, and you see a preview card of the most recent post.