Nice, I also like your introduction very much. I think for discussions that go into multiple directions, there should be some overview over the whole discussion

Nice, I also like your introduction very much. I think for discussions that go into multiple directions, there should be some overview over the whole discussion to see how the different branches are connected and also a view to focus the branches separately to go into depth and start reading. I think a graph can really help to get an overview as it can capture more information about how posts are connected. Also, maybe "reply" is not the only relation which occurs in a discussion. What do you think about a graph-based model?