It's definitely possible. You can order "answers" by date, disable comments and voting, then update the theme and language files so it looks like a forum. You can use categories for separate "boards" if you like.
I've looked into this myself, and at one point was planning on releasing a Q2A fork that works like a forum.
However, you will run into a performance problem if any thread has more than around 100 replies, because Q2A fetches all answers from the database whenever you view a question, and processes them all whether they are displayed on the current page or not.
That's something I'm hoping to fix in Q2A at some point (because it improves Q2A's performance too when there are many answers) but it's not high priority right now.