It would be for "related" to comics. So you wouldn't have redundancy. If someone out of habit put a Flash movie tracking film in the regular SF&F forum it would get moved to the Comic Book Movie/TV/comics sub-forum.
I think the reason we only have 2 lump threads for all of Marvel/DC may be that we haven't had the space to try a Bat family thread, Supes family thread, Avengers related type discussion threads.
I could see people having first time viewing or rewatch threads for Lois&Clark, Smallville, Flash. Superfriends retro talk. Best comic themed avatar threads.
Related, not specifically the books themselves.
For comparison sake: Dr.Who has a forum and the contents of comics covers as much and produces more than just Dr.Who and Torchwood. BSG and Stargate have active sub-forums but no new content. I'm not saying any of those come down, I participate in the SG one. Just saying there is constantly new content for Comic related material and interest in discussion of said content.