User blog comment:FairyRaven/Fairy Tail Chapter 337: The Golden Plains, Review and Commentary/@comment-4933386-20130628120559/@comment-15267891-20130628143036

The Golden Plains stands for a bright future. Since the events of July 7th was changed, no 10000 dragons, the mages did not die and despair was prevented. Future Lucy used the Eclipse Gate a few days after July 7th so after the gate was destroyed, her body returned to that time. So i think that scene is not in heaven, but a few days after July 7th. That scene is about Lucy and Natsu fulfilling their promise about protecting Lucy's future. (Chapter 324 when future Lucy died).