I love how Hiro placed the Rave gang there :T_T: but does this mean they will participate in some way?, or they'll just make cameos all over the place? Either way, I'm happy to know Hiro doesn't forget about Rave 
Theory
If Lucy is really going to close the gates, the only reason for that to happen is if the Cannon will destroy either all the mages or the celestial spirits, I believe so because we really don't have any information in what role did the 12 golden keys took part here; simply opening the gates?
Now, if there are Ten thousend dragons coming to destroy the kingdom, then being no sights of them from anywhere could either mean they're not coming or (going crazy here) they're coming through the gates O_O wich could be another reason for lucy closing them.
Also, what is this request from Jellal to Lahar and Doranbolt? And what's the reason for Rogue to come back to the past other than kiling Lucy? Save Frosh? o-o
Theory
If Lucy is really going to close the gates, the only reason for that to happen is if the Cannon will destroy either all the mages or the celestial spirits, I believe so because we really don't have any information in what role did the 12 golden keys took part here; simply opening the gates?
Now, if there are Ten thousend dragons coming to destroy the kingdom, then being no sights of them from anywhere could either mean they're not coming or (going crazy here) they're coming through the gates O_O wich could be another reason for lucy closing them.
Also, what is this request from Jellal to Lahar and Doranbolt? And what's the reason for Rogue to come back to the past other than kiling Lucy? Save Frosh? o-o