There is no such thing as happy endings in Westeros, but even by those standards the latest Game of Thrones fan theory making the rounds on Reddit is bleak. HelloGiggles spotted the theory from redditor zroberts1207 who postulates all the Starks must die by the end of the series. That sound you hear are hearts breaking everywhere.
The theory is based in part off of George R.R. Martin's previous working title for the final book in the series, A Time for Wolves (the book is now tentatively called A Dream for Spring). Rather than see the title as a hint that the Starks will rise again, the redditor suggests it hints at division among the living Stark children as the North allies themselves with different members of the family. In the book series, only one Stark child has died — that would be Robb — but in the television series the Winterfell inheritance pool will either go to Jon, Sansa, Arya, or Bran — barring any unexpected deaths on the horizon.
That is just the first half of the theory though. The second part is based on Leaf's speech to Bran in Season 6. Remember, Leaf warned Bran one day the direwolves would disappear just like the unicorns, mammoths, and lions. "The direwolves will outlast us all, but their time will come as well," Leaf said. "In the world that men have made, there is no room for them, or us."
Now, for the theory to make sense, Leaf would have to be speaking in metaphors. The direwolves have always been connected to the Starks — they're even on their sigil. Instead of taking her words as a warning of man's effects on the creatures who inhabit the world, Leaf's statements would need to be interpreted as a warning to Bran that his family's time is limited.
There is one big whole in this theory, and it rests both in the former title of book seven, and in Leaf's speech. A Time for Wolves doesn't sound like the end of the Starks, but rather their rebirth as they alone can rally the North to stand against the White Walkers and the coming winter. Secondly, Leaf tells Bran the direwolves will outlast everyone, even the lions. In the words of the late, great Ned Stark, "The pack survives."
Season 7 spoilers strongly suggest a major Stark reunion is in the works. I have no doubt both Sansa and Jon, and Sansa and Arya may clash over trust issues, but even if they disagree on how Winterfell should be resurrected, that doesn't mean they will turn their backs on each other. They weren't raised like the Lannister children; the Starks know their survival depends on them standing by one another.
Since this is Game of Thrones, there is no guarantee any Stark will make it to the end. However, if the Starks fall once more, I believe they will fall together, not because they have triggered a war in the North. With more Stark reunions on the horizons, it is the divided Lannisters who should be watching their backs, not Ned and Catelyn Stark's remaining children.