This. I think Arya will end up as some kind of leader in the books.
That being said, I somehow doubt, that the main character's ending will be that different in the show and the books. By main, I mean Jon, Dany, Tyrion, Arya, Bran and possibly Sansa, Jaime and Cersei.
Any one of them may die. If not, I believe Jon will sit on some kind of throne (North or IT), and Arya will decide to stay with him. It's him, she is going home to, not Winterfell. I think Bran will die - as the 3ER, I expect some kind of connection to the NK's power, and maybe he has to die, so the NK can be killed. Jaime will kill Cersei, so I'm pretty sure she will die, and Jaime, too. If not, he might become some kind of Lord somewhere, or he can continue as Kingsguard and keep protecting Rhaegars son. Or Night's Watch, if it's still a thing after the Long Night 2.0.
But I don't know about Sansa. If Jon sits the Iron Throne, Winterfell will be hers, so she will get what she wanted. (and I'm not sure, I want that, LOL.)
Because, as others have noted above, Sansa is D&D's favourite. They dumbed Jon down so that Sansa would appear as more intelligent, and would shine in Winterfell as some mastermind (and I fail to see her as someone like that). Now, that Jon is gone, he somehow managed to regain common sense. But Arya arrived at Winterfell, and I'm seriously worried about how that will play out. And no, I don't think Sansa would betray Jon. But somehow I wonder, what kind of character-assassination will happen to Arya, so that once again Sansa will be the smart one and the one who solves problems (Littlefinger...). That being said, I don't mind if Sansa is the one who brings down Littlefinger - but I will be terribly upset if they dumb down Arya in order to do so. So I keep my fingers crossed that Sansa and Arya manages to work together, Sansa manipulating Littlefinger and Arya seeing through his bullshit, Bran providing some info, and in the end, Sansa can finish him.
On a side note - I have no idea how the season will end, whether Jon learns the truth about his parents, whether Cersei is defeated by Dany (I don't think she will die, but she might lose all her powers and allies, like Euron). Maybe Dany manages to take the Iron Throne, sits on it, and that's the end of the season. But whatever it is, and whoever seems like the winning side, I think that will completely change in the last season, even if it's just 6 episodes. So I keep my fingers crossed, that even if in this season Sansa will outshine Arya in Winterfell (and sadly I expect her to do so), in the last season they will surprise us, and Arya might get something back from her book-character.