I have no idea if I would find this useful in the long run. However, I don't feel entitled to vote against a feature because I might not use it. I can certainly see how this may be useful, and that some users might love it.

The only downside I can think of is that many of us log on from work. While we can take a few minutes here and there to post to a "forum", keeping a "chat" open is crossing the line. I don't think that would kill this entirely, but it might discourage many users (like myself) from using it.

how would wediscourage people from asking and answering questions there in chat form?

Easy: no rep. If you want to earn points for your q&a, use the correct site!