I'd really like a wiki that also had discussions built in.
I've been thinking about this wiki thing for a while. I came to the conclusion that we need to take a step back and look what wikis offer us and what is annoying about them. The way discussions are organized is only one of the things we could do better.
For example when we look at non-wikipedia wikis, e.g. wikis used for documenting the history of a project, pages tend to become too unstructured. I've seen many wikis on the web that seemed like people use them for "I'm gonna put this down here, so it's documented and I'll find it again later". With some look, the author will find it again. In many cases though, noone else will.
My point is, wikis aimed for a sweet spot between structure and free text. For a certain use case. Our world changed, our tools changed, and, as a result, the sweet spot changed. I'm not sure how it's going to look like, especially how to handle forks, but that one might be related to the problem of merging threads of discussion.
One idea could be to use a per-wiki/page/chapter follow feature. I follow a few people and auto-merge their edits on the specified wiki/page/chapter. This would be recursive, so if they follow someone I don't follow, their edits trickle through to me.
This way would also address my main problem when reasoning about systems based on scuttlebot: I have a hard time understanding what happens on the edge cases of replication. That does not only apply to the wiki problem though, but to everything on here. What happens if someone I can see reacts to something that happened outside my scope? That kind of stuff.
Finally, let's not forget that one of the most important features of a wiki is that wikis need to be able to be private. For that we need groups (or netsplit-as-a-feature, but I'm hesitant on that one).