Again !!!spoiler alert!!! continue at your own risk!
Anyway after the last Manga chapter many people speculate that Mashima is gonna pull out a dragon ball (future comes to past to help the present so as to fix the future-or something like that).Generally that would -in my opinion- suck big time!!!
BUT!!!!!! I would love to see Fairy Tail (main) members as adults!!! And since Mashima lost his chance to show us an adult FT when everyone had disappeared from Acnologia's attack, WHAT IF he uses that way to introduce us to adult FT?? (Imagine a 30-year old Gajeel!!! :O )