People keep calling "To Kill a Raven" the final fight, but I think they are all wrong. If you take into account the line from Cid about Louisoix and the 2.0 trailer, it is glaringly obvious that something bigger than defeating Darnus is going to happen before 2.0 lands.

"Yet the bravest among us were spared, sent beyond the reach of time" is a very revealing line from the trailer that makes me think that we are going to succeed in preventing Eorzea from being completely destroyed but fail in preventing a major catastrophe (thus the world being reshaped). Our character is going to some how be spared by some kind of aetheryte magic that freezes us in time, a sort of stasis if you will, and we emerge a few years later in the reborn world.

As for Darnus, many people have speculated that he will become Odin. That seems even more likely after To Kill a Raven because his essence was absorbed into Dalamud. We know Odin is coming and the resemblance is striking, I'd wager that he turns into him and is released during the upcoming apocalypse.

Baelsar is definitely going to take advantage of the situation, possibly even make an attempt at the throne considering how ill Solus zos Galvus is said to be, but I'm not sure if he is pro-unification of all the nations or if he wants to end the attack on Eorzea.