Err.. this is a forum, there's no such thing like what your saying. Threads run their course until there's nothing left to say. And a thread's topic changes over time to different topics that somewhat relate to the main post (in this case a "convergence" device). For example, people have been talking about what should be in a convergence device or what featurees it should have. If a thread gets to far off course a moderator can then fork it though.