I think TB3 has a way to do this. However, its still pretty rudimentary. For example, if Im in threaded view and the thread is closed, I can click on the first email of the thread and it shows me the conversation-style message. However, it seems like each conversation has a limit and so after a certain legth of the message, it shows ... if you have too many messages in the thread then you just end up with PersonA ... PersonB ...

Useless.. but hopefully something that will be customizable before 3.0 is released.