Just made a connection last night between Aftermath and what little we know of the Battle of Jakku that I can't believe escaped me at the time. Throughout the book, Moff Pandion keeps harping on the fact that Sloane is keeping the only Super Star Destroyer in service, the Ravager, hidden from the rest of the Imperial leadership. If there's only one SSD in the months after ROTJ, it has to be the same one that ends up wrecked on Jakku that the Falcon flies through in the second TFA teaser. This seems to be a strike against the theory I've seen tossed around that the mysterious Fleet Admiral at the end is Snoke, because the Admiral commands the Ravager and one would think it likely he'd go down with the ship. Of course, it's possible that it is Snoke and that he's no longer in command of the ship at the time of the battle, but I think it's more likely that we get either a new character in the vein of Thrawn (or, fingers crossed, a re-canonized Thrawn himself) mounting an Imperial comeback during the rest of the trilogy and ultimately having his last stand at Jakku.