I think the bigger issue is that there's nothing preventing the Dragon Slayers from turning into dragons now. On the other hand, Mashima will probably use this to fuse all the slayers into a single dragon capable of defeating Acnologia because friendship.
I think that's what the "dragon anti-bodies" were supposed to be for - to make it so that it's impossible for them to become like Acnologia. Then again, I might need to re-read the chapters, or read a different translation, to refresh my memory and clear things up.
The whole "memory modification" thing from Sting and Rogue's dragons came out of nowhere and seemed kind of pointless, but other than that, we got an explanation for why the dragons vanished that actually used material that we had seen already to justify it, so that's a plus.
I don't know if the arc's done or if there will be a chapter or two of wrap-up, but so far, this was one of the better Fairy Tail arcs - a broader amount of characters got focus, the power-ups that were given made sense for the most part, and we seem to be building up to a conclusion seeing as Zeref, Acnologia, the death of Lucy's mother, and Lumen Histoire seem to be the only major plot points that haven't been addressed yet, and it seems like they'd all tie together (we don't have a specific date for the death of Lucy's mother, only that it was in the same year as the disappearance of the dragons, but we also don't know how it happened unless I'm forgetting something). We'll probably get a short comedic arc in between (that tends to happen with this series, and it generally helps to take a break between the heavy stuff - take Davy Back Fight, for example), but unless something else becomes the basis of an arc (restoring Aquarius's key, for example), we might be nearing the end (relatively speaking - could be two to three more years).