User blog comment:IamJakuhoRaikoben/Chapter 412: Dance Unto Ishgar, Review./@comment-5288632-20141208162854/@comment-9595671-20141208165900

I agree, its pretty much been solidified he's the last boss, I always thought it would be Zeref until Zeref kept mentioning him. And when Zeref was shown to actually be scared of Acnologia it all became clear, especially when we learned Zeref had a hand in making him a dragon.