I remember in an interview that Montomu Toriyama said this about Serah:
"Toriyama: Lightning’s goal is to figure out how to save the world.
Toriyama: About Serah, let’s just say that she went on journey to “save all” for now."
So, it seems even though Serah is dead, she still has a significant role in the next game, i wonder what it could be. She has to "Save all" somehow, I think maybe she will be the catalyst that can revive Etro and fix the timeline. While Lightning has to save the world, Serah could somehow revive the goddess and rebuild the timeline and stop the events of XIII-2 from occuring.
I remember in an interview that Montomu Toriyama said this about Serah:
"Toriyama: Lightning’s goal is to figure out how to save the world.
Toriyama: About Serah, let’s just say that she went on journey to “save all” for now."
So, it seems even though Serah is dead, she still has a significant role in the next game, i wonder what it could be. She has to "Save all" somehow, I think maybe she will be the catalyst that can revive Etro and fix the timeline. While Lightning has to save the world, Serah could somehow revive the goddess and rebuild the timeline and stop the events of XIII-2 from occuring.
Here is the link for the interview:
http://www.novacrystallis.com/2012/09/lightning-returns-final-fantasy-xiii-developer-interview/