I agree for the most part about the Seanchan being the major upcoming antagonist, mainly just for this book though. It seems only proper that the shadow and their forces are the main antagonist of the last book. This isn't to say that the Seanchan won't still be antagonist going into AMOL, but that's obviously not going to last.

Correct me where I'm wrong but my theory is it will be the Seanchan who launch their second major offensive on Caemlynn/BT with Traveling this time. In TGS when they were discussing their assault on the WT, there was another map mentioned but of course weren't told what it was. It's either the BT or Caemlyn. So the thinking is once they get Traveling and they will get it in time for everything that needs to happen happens at Caemlyn in the climax.

How all this will fit in with Mat away at the TOG and a battle raging at Caemlyn or about to commence I don't know how this timeline will work out. Will Mat make it back before the battle starts, during or after? It would be a huge disapointment if he missed it. His relief in the spoiler chapter 'The Seventh Striped' lass about not having to be at the Succession War seem to be major foreshadowing that next time there's a battle at Caemlyn he won't be so lucky.

So a huge battle with (fingers crossed) Mat's canons defending Caemlyn and annihilating the Seanchan at the battle of Caemlyn with both sides suffering defeasting defeats nonetheless. This would fit with this book being even darken than TGS. The epilogue of the book is swapping between the main players of the light and how bleak and beat down they are after this disaster. And to top it off, Rand could possibly die here and that would make everything even more dire.

On the other hand, I could be totally wrong and it's all Trollocs/Dreadlords and shadowspawn that attack Caemlyn in monstrous numbers. Meanwhile the Seanchan are still sitting on their thumbs in Ebou Dar fuming in anger that The Dragon Reborn etc. still defy them when the LB is immenent and 'clearly' the Empress is going to lead the Light to victory and send the Dragon Reborn into SG to battle 'leafblighter' - sarcasm off. Regardless, this would be lame to the ninth if the Seanchan play no role in the upcoming battle. The plot required them to acquire Traveling so they could meet their destiny (of getting slaughtered with the Prince of Ravens canons baby) at Caemlyn imo.