Warning: This list contains spoilers.
Before Season 7 of Game of Thrones began, there were rumors that the Wall would fall, answering the question “Can the Wall in Game of Thrones be destroyed?” Why, sure it can! After all, why would George R. R. Martin create the largest man-made structure in this world and then just let it exist forever, all Wall-like?
Does the Wall in Game of Thrones have magic? Yes, indeedy. A regular old wall is not enough to keep back a horde of undead soldiers. The Wall was created with the ancient magic of the Children of the Forest to repel the Night King and his White Walker army after the last Long Night. And now it seems like we’re headed for a big showdown with the rest of Westeros and its huge, magical, icy protector is at stake.
If the Night King manages to overcome the magic embedded in the Wall, thousands of White Walkers and wights will spill into the North and, eventually, the rest of the Seven Kingdoms. Cersei thinks she’s got problems now - just imagine a bunch of wights storming the Red Keep.
Will White Walkers breach the Wall, leaving it intact for the most part? That’s a possibility as well, although highly unlikely. Just unwarding the magic may be enough to let them through. However, the Night King seems intent on going big or going back to the Land of Always Winter, so a huge Wall demolition may be in order.
Speculation about the Wall’s demise is heavily tied in with Night’s Watch theories. With depleted forces, they don’t stand a chance with a real White Walker invasion. Hardhome, anyone? But will the big ugly twist see Eddison Tollet, acting Lord Commander of the Night's Watch, become a wight? Please, noooo!
According to Westerosi history, Brandon the Builder constructed the wall roughly 8,000 years ago along with the Children of the Forest and some giants. He created the structure, mostly made out of ice, after the War for the Dawn, a war between the First Men (allied with the Children of the Forest) and the White Walkers (called the Others in the books).
It is warded (that is, spells are embedded in its walls) with magic to repel White Walkers. The Wall wasn’t built as high as we see it now - 700 feet high and 300 miles long from the Gorge to the Bay of Seals.
But what if Brandon the Builder and company didn't build the Wall at all? Fan theories suggest the Others/White Walkers could have built it, either to mark their territory or to keep men away. Reddit user Naggers123 writes,
"The Wall existed far before the First Men came to the shores of Westeros, but what better way to extol the power and supremacy of humankind by claiming such a breathtaking monument as their own[?] Like Lann the Trickster, one simple act of deception has been able to establish a dynasty that has lasted for generations. The Starks are always friends to The Watch.
The First Men have invaded the native's lands, settling cities like Hardhome, establishing clans like the Thenns and brazenly sending their ilk as far north as their bodies will let them. The greed of man has driven them away from their homes and into the Lands of Always Winter.
And now the White Walkers want it back.
It's not an invasion, it's a reclamation."
When Alliser Thorne led a rebellion against Jon Snow and split the allegiances of the Night's Watch, he may have been sealing the Wall's fate. A lost prophecy that only Old Nan recalls states, "The monsters cannot pass so long as the Wall stands and the men of the Night's Watch stay true, that's what Old Nan used to say." Uh oh.
There's a legend that Joramun, who was once King-Beyond-the-Wall, blew the Horn of Winter and awoke giants to help defeat the White Walkers in battle. But what, exactly, is the Horn of Winter?
According to legend, the first time the Horn was used, it summoned the giants, but if it's used again, it will bring down the Wall. It's not clear where it came from, who made it, or what, exactly, it can actually do. But if someone finds that horn and blows it, there's a good chance the Wall is coming down.
How important is an Iron Throne when a White Walker army is laying waste to everything in sight, turning forces against themselves as the dead rise? Does it matter how many titles Daenerys Targaryen has to her name or who Jon’s parents are when everything is going to hell?
The Wall crumbling resets the stakes and refocuses the Seven Kingdoms on the real threat. What good is an Iron Throne when the world has been turned to ice and darkness?