You'll never see them with the current "industry standard" UI of sticking forums right there, on postlist. Unfortunately, the very definition of "subforum" is built around the very idea of sticking forums on postlist. That doesn't fly here. It's safe to say that "never' is about as good as it will get, as far as that's concerned.
We understand the need to represent nested ideas, but in our opinion, all of the current implementations suck. Until we can find a way to make it not suck, you won't see much that resembles subforums.
