I understand where you're coming from...Gaara had a very shady and sad past and was able to come through that. It makes me wonder, Sasuke may have always had this small part of him deep inside of him called insanity. Maybe it even started to die away until he ran into Itachi once more and he made the memory of his parents/clans deaths as clear as the day it happened.
Okay, I will try to elaborate with your comply the best I can. I am not Kishi and I don?t know if what I come up with could be the answer. However, remember how Gaara was in the past before he was changed by Naruto? After his uncle betrayed him he became unstable and decided that he would kill to make his existence known. His victims consisted of Team Shigure because Gaara claimed they looked at him the wrong way.
He critically injured Lee during the Chuunin Exams and then tried to finish him but was stopped by Gai. Dosu became disillusioned after learning that Orochimaru branded the Ten no Juin upon Sasuke and that his team was a simple test for the Uchiha. He tried to kill Gaara so he could be the one to fight and kill Sasuke in the finals but was killed instead by Gaara. Midori/Tsuba pressured Gaara to lose the match against Sasuke and due to feeling offended he killed them both which luckily satisfied his bloodlust as he originally intended to target Shikamaru/Naruto. Gaara and his village agreed to assist Orochimaru in his invasion plan where his role lied in unleashing Shukaku in the center of the village but was unable to by the wound inflicted from Sasuke?s Chidori.
Gaara?s siblings even feared him as evident when Temari covered Kankurou?s mouth to stop him from reminding Gaara about the plan because she feared that as a result, he would kill him. He tried to kill Sasuke/Naruto while he was pursued after fleeing the Exams. Aside from his murderous desires he also had to withstand insomnia due to Shukaku completely taking over his body if he were to fall asleep (the lack of sleep can cause just to name a few symptoms psychosis, hallucinations, death etc.). In which caused him further instability and plunged him further into "darkness" via a burning desire to kill. The reason I used Gaara to help me answer your question is because he is a perfect candidate as Gaara is similar to Sasuke with the darkness/damaged mind due to his past.
Now approaching my point, wasn?t Gaara a serial killer holding no remorse and was later turned as a result to Naruto?s "changing abilities" and was pardoned by his village/even went as far as to becoming the Godaime Kazekage despite his criminal background? He never became a Nukenin unlike Sasuke as he remained in his village. The crimes Gaara committed were far more extensive than the ones Sasuke committed; they mainly consisted of murder but he was still accepted by his village. Konan can be another proper example of this as she was in a criminal organization hence Akatsuki which is only the most wanted group in all of the shinobi world and for being a member she became known as a criminal/Nukenin alike that of Sasuke?s label. After Naruto changed Nagato she chose to follow Nagato?s decision turning as well and became the leader of her village.
In other words her own village pardoned/excepted her much like that of Gaara. So if Konan/Gaara were able to overcome a fate of trial for murder etc. than I think Sasuke should be given the same chance if he is indeed turned by Naruto, ne?
@Poison Ivy if you read this recent post, can you continue to not agree that Sasuke might still have a chance to change just as Gaara/Konan/Nagato indeed were able to?
Sasuke was treated with nothing but respect when he entered the academy and progressed just as everyone expected the last remaining Uchiha should. He joined his team and found that he truly cared for them as his own family...And maybe that frightened him. It's hard to keep in mind that these characters of those of Kishi's and that everything they do is because he draws it out and writes in the text. It's hard to believe that Sasuke is completely lost and that he doesn't know what he's doing. He after all, didn't kill Karin. Though, that doesn't say anything at this point.
Sakura and Naruto have searched for him with the hopes of bringing him back to Konoha, because they both love him. Until recently they were both still searching for him to bring him back, and now it has all changed. Something has to change about Sasuke or he will never be able to go back to Konoha. He still has it in his mind that he needs to be an avenger. Something about that needs to change, and maybe Sasuke knows what this whole time. Maybe Madara is just using Sasuke.
Kishi has constantly pushed the idea of never giving up hope in his manga and as hard as it seems, that's what we have to keep doing I guess...Ahh, so much to think over!