Hmm. No sign of the dragons... Maybe the dragons came from the other side of the gate?
Spoiler
I am pretty sure this is it. Future Rogues main objective is to get the door of Eclipse opened, It's almost certain that this guy is evil for killing Lucy and trying to Kill Gajeel. Dragon's are known to be almost extint in the current times so where the heck would 10.000 come from?. There's no sight or even proof of the Dragon's raid (and there should be, with less than 12 hours before the attack, there should be some sightings). The main purpose of the door was to travel back into the past, before one man turned into Acknologia and Zeref became... Zeref. Lucy tries to shut the door...
I mean everything seems to point to that they unintentionally open a path to the past with the gate, to the times of the great war, and all the dragons just use it, come to the present and that's it, the so feared apocalypse caused by themselves. I'd be willing to bet this if it wasn't because FairyTail has been damn inpredictable during this whole arc.