Interesting. I think we'll see one final battle this season and the other next season. One will be against Cersei and her army and the other will be against the White Walkers. Since they haven't seemed to focus much at all on the White Walkers this season, I think it's more likely we'll see the battle against Cersei wrap up this season, leaving Daenerys and Jon to go against the White Walkers in the final season. I do agree it makes the dragons more vulnerable now. They couldn't write the script to make the dragons invincible. They had to add some suspense. Maybe the dragons get killed fighting Cersei and they have to defeat the White Walkers next season on the ground with dragon glass.