Okay, so here is MY crack pot theory on the future of Theon Grayjoy
As we already know (or at least those of us who read the Teaser Chapter for the next book, WoW) Asha wants Stannis to spare her brother. I think she will offer herself to help Stannis in some specific way. Maybe she will try to infiltrate Winterfell once Ramsey's host marches out to meet Stannis. She will sneak in with some of her Iron Born and lead some attack behind enemy lines and help Stannis to win Winterfel. Soemthing along those lines anyway.
Stannis, being an honourable man, will let Theon live, BUT, his crimes won't go unpunnished. Stannis is nothing if not fair, and 1 good deed does not wash out the bad, nor a bad deed the good. He can't really take his fingers, because Theon has precious few of those. Instead, he will be sent to live the rest of his "life" at the wall.
once at the wall, Melisandra will sacrifice him, since he is the son of King Balon (now deceased) and nephew of King Euron. So he will be burned and Jon (who is not dead... and more and more I am agreeing with Needle's theory that the jon who was attacked and killed(?) was not really Jon) will get a dragon who is raised from either the Wall, or from Beneath Winterfel.
Then Jon, with his Dragon, Dragon steel sword and Dragon Glass Armour (why not) will fly north and battle the White Walkers. (ghost will probably die somehow cause all those dogs seem to be dropping dead)
So that's my theory. As for my personal feelings toward Theon, I never really liked him, but I never really hated him either. He always seemed kind of spineless to me. He killed those 2 kids cause Ramsey (as Reek 2.0) told him to do it. He attacked the north cause his dad told him to. He kind of just does as he is told all the time. He definately didn't deserve what ramsey did to him though.