I think Theon will be instrumental when everyone needs to flee to the islands. I mean, wights can't swim, so, even though there is now a zombie dragon, I assume there's a chance people will be evacuated from the mainland. All houses who rule over islands will become protectors of sorts; Theon/Yara at the Iron Islands, Lyanna Mormont at Bear Island, someone at Harrenhal, perhaps, then I'll say Varys on behalf of Daenerys at Dragonstone... maybe some people will make their way out to Essos. Ok, the more I write about it the less it seems plausible, but who knows. It would give Theon more of a role than just going through all kinds of shit and maybe saving his sister (who needs to have a better part to play to be justified as a character I think).
