I read a thread asking what would be next after imageboards if they no longer have a place in the future, on 8chan/tech/ I think. I''ve been thinking about that question.
4chan is somewhat primitive in comparison to the newer imitations. 8chan and Endchan and the like allow for not only multiple file uploads per post, but also multiple file types, beyond merely images and videos. At that point, you have a filesharing platform that is only an "imageboard" in legacy. From there, we can abstract to the nature of a 'chan'.
What features make a chan? The list is surprisingly long if one gets fine-grained with the details.
>file attachments >anonymized by default >topic/theme segregation >centralized hosting and moderation >ephemerality of hosting >lack of profiles and microblogs excluding this thread >linear, chronological ordering of posts
And on you could go. Compare this to Reddit, and ask yourself whether you would be looking at a regression in either direction, or if they are both valid solutions to different problem sets, with their own separate lineages of progression and degeneration. I lean toward the latter stance; that position reframes the original question, "What will replace imageboards?". It entails the question, "What are chans for?". And that is a very big and complicated topic of debate.
But for the sake of this conversation, how about the answer of "Quick, no strings attached, discussion and file sharing"? That necessitates profiles not being a requirement, having the ability to share many and multiple types of files at once. Reducing user liability for what is posted is where wanting to increase anonymization comes in. Ephemerality of content, some say, is an essential feature of chans, but to me it seems to be more of a practical matter of how much data really can the host afford to keep. So while there is a baseline of data that needs to be kept for the site to be functional, there doesn't seem to be a limit or maximum amount of data that can be hosted.