Game Of Thrones: 8 Ways Season 6 Spoilt The Winds Of Winter (And 3 It Didn't)
4. Arya Goes Home

Arya's storyline this year actually started dipping into The Winds of Winter, as she witnessed a play in Braavos based on famous Westerosi events, such as King Robert's death and the Purple Wedding.
In the preview chapters of TWOW, this same troupe does appear, however Arya isn't merely an audience member; she's part of the play. The other, even more crucial difference is with the Waif. A big part of Arya's story in the show, and her rival in Braavos, she's more of a minor player in the books, and assists Arya rather than doling out merciless beatings to a blind girl.
Still, Arya needs to get back to Winterfell, and chances are good that it'll be happening in The Winds of Winter. Her time with the theatre troupe as Mercy will eventually lead to her making a decision to return to Westeros - and it could be in-part thanks to developing a bond with the lead actress in the play, and being given the task of poisoning her. Also in that preview chapter, she's seen breaking the rules of the Faceless Men again, killing Raif the Sweetling (in similar fashion to how she kills Meryn Trant on the show), which will probably contribute to that story coming to a close, and that in turn means leaving Braavos.
When she does return to Westeros, it also seems a given that she will be crossing more names off her list. While Frey Pies has already happened in the book, it's still likely that Walder will be a target for her vengeance, unless of course Lady Stoneheart gets there first. Because the story is moving towards its endgame, though, Arya needs to be back in Westeros regardless, and it will probably happening during TWOW.