Of course that wouldn't be the final battle. *This* is the final battle. Heathcliff, alive and well, finally makes his appearance and explains everything that had happened with Aincrad. Kirito then faces him for a final confrontation, before the very world they had been trapped in for so long begins to crumble, and the players are released fro the death game, one by one.
Before vanishing, Kirito and Sinon share a more intimate one-on-one moment before she's teleported out of the game. This is because I chose to bring her to the final battle, triggering the conversation with her specifically. That was a no brainer. The result of that choice also means a special ending scene with her later, which I'd been looking forward to since the day I got the game :]
Sayonara... SAO...
