Bounceounce
Member
Well for one, he can bring his arc full circle by using his knowledged to help retake Winterfell in the name of Stannis or the name of Jon.I think people are finding the logistics of it hard to understand and when it would occur. The show actually does a decent job of making it seem like he has to do it. The books have Shireen so far away from Stannis, with a dead Jon Snow who needs to be resurrected. Maybe Ghost is scarficed to save Jon?
What could Theon possibly add to the end-game of the book story? Show Theon is just going after Euron.
Secondly, in the event that Bran isn't leading Theon to the tree for a sacrifice, he can be used as an avatar for Bran or just have valuable information provided to him by Bran (maybe even get instructed to make a "Weirwood arrow").
Three, Dagmer Cleftjaw has been holding Torrhen's Square ever since ACOK,and considering that he's loyal to Theon/his true father figure, Asha/Theon could likely escape to him, or even sway Dagmer to join the cause of the north and Stannis which would give Stannis another valuable stronghold/white walkers if it comes to that/or the fight against Euron (I have no doubt that Theon and Dagmer will meet again).
Four, the Latecomer plan could still potentially come into play, we'll just have to wait and see about that.
Five, and all potential plot points aside he still needs to meet Jon Snow again which readers have been theorizing about for years, and the show just confirms it's even more likely to happen.
The idea that they're foils to each other isn't something that the show created, GRRM even made a detailed (unprompted) comment on the tie between the two of them just a week or two ago, it's going to happen.
Probably more I haven't even thought off.
Edit:
He didn't go through all of he's gone through just to die/be sacrificed in front of a weirwood, there's still character development that Theon needs to go through, hell I even forgot that he's probably going to see his mother again and resolve that plot thread.