As an aside - I think Fafnir's a good shout. We've had so many dragons in the game at this point that you can tell which names they're avoiding e.g. in WoD, the "Five-Headed Dragon" is traditionally Tiamat, but since they didn't use that name they were obviously saving it.
Similarly, Jormungand won't be one of the 7 or the mother or anything probably because the adds in the Queen Scylla/Xande Clone fight are Thor and Jormungand (likely a reference to Ragnarok). I know we've had name changes before but that was more to do with japanese naming stuff and there's a whole post from Koji about that.
So I'd go for Fafnir personally ... possibly Shinryu but I'm not sure on that since Omega is still very much in the picture and all, though again the likelyhood of them going with the Shinryu vs Omega branch of FF lore is in question.
