User blog comment:Miskos3/Fairy Tail 539: World Destruction, Review/@comment-26184007-20170610204900/@comment-2214433-20170610230335

Or perhaps you may want to try and read between the lines; the crack and Acnologia appearing happened before Natsu vanished, as it's obvious by the bottom panels of this page, we can see the repeat of the end of the previous chapter with Lucy crying and what not, plus, all the other characters are also reacting to Dragon Slayers disappearing the same way. Mashima just let us see Natsu go poof first for the sake of "Oh no, Natsu is actually dying" suspense.