Yes, they do. I have read at least one trip report, possibly two, from travelers who have been to North Korea. However, three threads (or even the 10 I count since 2006) are not the basis for a sub-forum. If there is enough interest to sustain a Korea forum, which I am uncertain of, but I can conceive of the possibility, then it would make sense for North Korea to be included there, but to carve out a sub-forum just for North Korea which would have one thread every year or two just doesn't make sense.

To quote the Talkboard's posted criteria, "one living forum is more valuable than two mostly dead ones."