User blog comment:FairyRaven/Fairy Tail Chapter 337: The Golden Plains, Review and Commentary/@comment-4933386-20130628120559/@comment-1359322-20130628124345

@Shin here the point, there's 2 futures:

Future 1 : Gate Opens - 10,000 Dragons appear Future 2 : Gate Closed - Acnologia appears

Even if the 10,000 Dragons didn't appear Acnologia would, and there was only 10% on Humanity left in 7 years after Acnologia controlled the world.