Some clever readers have long since figured out how A Song Of Ice And Fire - and, subsequently, Game Of Thrones - is going to end.
The upside is that they have absolutely no idea that they were right, and George R.R. Martin isn't giving anything away. While he's admitted that among the countless theories you can read online there is some truth, all he'd actually say about it is that he won't be changing his mind, and that it'll be bittersweet. I don't think anyone really expects a happy ending anyway, so that doesn't give us many more clues to how it's all going to play out.
What is likely is that we'll find out by watching it before we read it. The TV series is going to end with Season 8, meaning that it'll wrap things up in 2019 (dear God that is way too soon). Martin hasn't even finished the 6th book yet, so getting the 7th out before then would require nothing short of a miracle at this stage.
So, with just a year until we discover exactly what happens to Daenerys, Jon, Tyrion, and all the rest, what about those theories? There's plenty of them, from the mad to the magnificent, and as it stands, they're all a 'maybe'. These are the best fan theories about how these violent delights will come to their violent end.