I agree it might be difficult to identify the entire thread since its actually a reverse-linked-list from the top (the first post is actually the end of the list). To find the next element, you need to load all replies anf see if the same npub replied directly to itself.) But if you recurse in a limited fashion (maybe load only 3 or 4 elements of the thread at a time with a "show more" to avoid infinite/circular thread attacks) it should be functional and it will allow viewers to see the next post in the thread right away. It could be as simple as just putting the authors direct replies at the top of the response list.