Aerc can display a thread in a tree-view of a directory, yes. Run :toggle-threads to see it (I'm using Maildir backend).

Using notmuch backend, one could also have a key to display all the emails that are in the same thread as the current one, so that you get a nice conversation-like view which includes sent emails as well (Purebred does this by default, for example). This is not supported out of the box yet, but I'm thinking of implementing a patch for it in the coming weeks.