That's the rub. Unless both Cid and Graha bite the dust, it will always be on the table. Cid is way too useful a plot device to kill off and Graha is just so darn likeable that fans would be upset if they lost him a third time. I honestly can't see how they wouldn't add more to the story at every convenient opportunity.
I would personally prefer it if, if they do go that route, it is to update the game once more with a nice time skip, or dare I say it, an undoing of history to set things right (Yes, I want to save my favorites from their fates. I'm selfish, fight me). Yoshi did say that any major changes to the games battle systems and character rigging (skeletons and clothing) would be at 7.0 at the earliest. That's right around the corner.
Final Fantasy XIV: A World Rejoined...
The rest is just musings of an over active imagination.
I think Zenos is a red herring and is just a way of showing how conniving the true antagonist of the story is. Fandaniel is just way too happy to be free to do as he pleases to be a hype man for someone who has the most boring reason of all time to gather strength. I suspect a mass sacrifice is to take place relatively soon (he is, after all setting the stage for Zenos' rampage)and is just using the chaos to gather aether for summoning Zodiark for Zenos. But is he really? That's my question. It sounds a bit lame if you ask me. All this time losing friend after friend, just for it all to come down to a magic mecha fight between Zenos piloting Zodiark and the WoL/WoD controlling Hydaelyn? Yuck.
There is something that does interest me though, and that is whatever made the sound that drove the Ascian's magicks to run wild. Zodiark was made to deal with it sure, but it seems just too enticing a mystery to not be explained further. What if instead of trying to summon Zodiark for a brat, Fandaniel summons a weakened Zodiark for whatever made the sound? Sounds about right to sacrifice the very thing used to stop it the first time (Maybe Hydaelyn too). This is a man that wants chaos. Causing a repeat of the Final Days? If I was a mad man hell bent on causing chaos in a world of magic and possibility, that would be my goal.
Or it could all just be a fight between us and Zenos to determine who is the strongest idiot. Just clubbing each other over the head till one of us falls over dead. I'll go first.