User blog comment:FairyRaven/Fairy Tail Chapter 337: The Golden Plains, Review and Commentary/@comment-2214433-20130628095736/@comment-1776824-20130628101939

Mashima made it pretty apparent as to why everyone disappeared. In one year, Frosch is going to die, leading Rogue to turn into what we saw, meaning he's going to go back in time regardless. With the Eclipse Gate destroyed, Rogue may grow up to be Future Rogue, but now he cannot go back to the past. As he cannot go back to the past, the Eclipse Gate was never opened, meaning that all the Dragons could not come into the present, which lead to the Dragons being sent back to their own time period, as well as the two Future beings...more or less.