Well a lot to take in. First of all like I and many others also thought this is when Natsu will find out everything, that he is E.N.D., that Zeref is his brother, we also found out some information our selves.
The dragon slayers being over 400 years ago, I think this finally answers the questions of why Natsu and Gajeel couldn't make it out of Fried's ruins in the Grand Festival arc, now that question is hopefully put to bed.
As for the dragon slayers being orphans, maybe they don't have that memory, maybe if they get that memory back, we find out they knew each other long ago, that would be cool.
Zeref and Igneel were friends? Well we do know what we all thought of why Igneel couldn't kill E.N.D., also E.N.D. was not the Tartarus guild master, that was just something Mard Geer made up.
So we find out Anna was the celestial spirit that sent the dragon slayers to the future, and Layla is the one that recovered them, we never Anna's face, but I do have a theory, it can't be a coincidence, that Anna is probably Lucy's ancestor. We may never find out, but that wouldn't surprise me. We still don't know who Brandish fits into all this.
The biggest shock is Zeref life is connected to his demons, if Zeref dies, so will Natsu, at least that is what we are to believe, I don't know if that is true, I don't know if Zeref himself knows if that is true. Zeref continues to be the most bipolar villain ever, I want to die, I want to destroy the world, I want to die, I want to destroy the world, make up your mind.
Anyway also chapter, looks like Natsu blew it, thank to Happy, though it is not like Zeref was going to die anyway.
Next chapter titled Assassin, who could that be about maybe the Alverez empire has a sniper, though that doesn't fit their style.