If you've been glued to Game of Thrones since the beginning, you probably fell out of your chair watching the season seven trailer. The most powerful families in all of Westeros are finally about to converge, and blood will be shed! There are so many petty squabbles and romantic trysts on the show that sometimes it's easy to forget that there is an ultimate goal on Game of Thrones: win the Iron Throne, and become king/queen.
Right now, Cersei is sitting atop the the throne, but the Starks and Targaryens are coming for her — and they have armies. So when you hear Jon Snow utter, "the Great War is here" at the end of the trailer, you may have assumed that he's referring to the imminent battles between the families. It's absolutely a possibility, but there's something larger at play here. Yes, all the houses are climbing over each other to assert their power, but they're eventually going to band together to fight the real evil: the Night King and his undead army.
Entertainment Weekly recently revealed that season seven is going to move along at a much faster pace than we're used to. "This season is really different than any other season because it's accelerating toward the end," said Kit Harington. "A lot of stuff collides and happens much much quicker than you're used to seeing on Thrones. . . . It's so different than what everybody is used to. It's quite exciting."
This, paired with the new poster of the Night King, has led us to believe that the upcoming episodes won't focus on the fight for the Iron Throne, but rather the war between the humans and the White Walkers — thus, The Great War.
The theory is further supported by a moment in the latest trailer. Davos says, "If we don't put aside our enmities and come together, we will die. And then it doesn't matter whose skeleton sits on the Iron Throne." This suggests that he is very aware of the threat posed by the White Walkers, and the people of Westeros will either be wiped out by the Night King, or the battle for the Iron Throne will need to be put on hold.
My (educated) guess is that the upcoming batch of episodes will feature the families uniting against the White Walkers — all except the Lannisters. Cersei is too proud to partner with the Starks or the Targaryens, and it will lead to her downfall. Together, Dany and Jon will lead the march against the White Walkers and defeat them, and the final episodes of the series will be about rebuilding after the Great War. Boom.