Sasuke could have chosen anyone to be a part of Team Taka, hell he could of even gone back to Konoha and try to persuade Sakura to go w/ him...but he didn't. Out of all the capable medical ninja that are in the shinobi world, he chose Karin. If he ends up w/ anyone, my money is on her. He's only respected Sakura as a friend, and even that is barely. Never even apologized for attempting to kill her 3 times. SMH. That, and Sasuke has said many times that he values people only for their power. Sakura is from a civilian clan, he will probably keep that in mind. Karin is an Uzumaki and Sasuke is an Uchiha. If they ever have children, they will be OP. That and Sasuke has always been impressed by Karin's abilities. (He was impressed by Sakura's punch too, but everyone was so does that really count?). He even called Karin intelligent when he came for her and was amazed by her sensing abilities/ healing.
Naruto still loves Sakura and Sakura is the only girl that has ever supported him. Hinata supported him, but it was only on the inside, not outwardly like Sakura did. Hinata's support never quite helped Naruto the same way that Sakura's has. Also, Hinata isn't in love w/ Naruto...she only loves the fact that he is inspirational and his nindo of never giving up. She is confusing her admiration for love. People also claim that Hinata loved Naruto from the beginning, but no matter how you put it...it's simply a false statement. Hinata was the only child to realize that Naruto was suffering at the malice of the village and their antagonism...but only got a weird confidence out of it because he was worse off than her. She didn't even try to say a few kind words to cheer him up or smile his way. That's so wrong on so many levels. She trumps everyone in favor of Naruto. EX: Neji died and she went to instantly fangirling Naruto's hand. Kiba vs Naruto at chuunin exams in pt1--->wants Kiba to lose, her own teammate, so the crush she never spoke to even once can win. Her team barely makes it out of the Forest of Death and Kiba/Shino say that they are relieved that the team is okay---> Hinata sees Naruto standing next to Sakura/Sasuke and thinks "Yay, he's okay" w/o thinking of her team. I could keep on going, but I won't. NaruHina is just a one-sided infatuation/obsession on Hinata's part. Naruto is like her rockstar. Development needs to be on both sides.
Sakura. The person she smiles the most around and even blushes the most around is Naruto. When she first sees Naruto in Shippuden, she thinks he's attractive. She and Naruto have gone on dates, hugged, etc. They have regular conversations, make each other laugh, have seen each others saddest moments, comforted each other, and their personalities mesh well together. People have even commented on how well they work together including Tsunade, Jiraiya, Kakashi, Iruka, etc. Minato, Ino, and Jiraiya, and Konohamaru have referred to Sakura as Naruto's girlfriend. Naruto even said that she was pretty much his girlfriend and she didn't deny it. You can obviously tell that she hasn't been caring about Sasuke during the entire war arc. When Sasuke showed up, she didn't fangirl, she was surprised. This was the very guy who tried to chidori her head off a few weeks ago and told her that he was going to destroy her village and now he was helping her and Naruto in the war and wants to become hokage. Who wouldn't be surprised? Then, she asked Hinata about Naruto's safety first than Sasuke. Later on, she only thinks of Naruto and never Sasuke. Right now, Hinata is out of the picture, and Sakura is healing Naruto/ keeping him alive. She literally has his heart in her hand. And she hasn't thought of why Sasuke has been absent all this time. Karin is rushing to save Sasuke. Sakura no longer loves Sasuke on a romantic level, only as a comrade. Sakura is also the only girl to be connected w/ Naruto's hokage dream and was the first to support it, even all the way back to the chuunin exams in pt 1. This war arc has been trolling NaruHina to the max and shipping NaruSaku/SasuKarin. Sasuke even apologized to Karin. Since when has Sasuke ever respected anyone enough or been humble enough to apologize to them? Oh yeah. Never, only Karin.
NaruSaku and SasuKarin have development from both sides, whether anyone likes it or not. Hinata's never even been involved w/ the two most major things in Naruto's life: Sasuke/ his hokage dream. She literally knows zilch about them and has never even been remotely associated with them. According to Kishimoto, the manga is ending this year. That means that we have 40 chapters or less to wrap up the story and have Naruto get back Kurama or get another powerup, Sasuke needs to get revived, Sasuke's resolve for hokage needs to be elaborated on, mystery man must be revealed, Madara being defeated, the Edo kages going back, the case of the juubis getting taken care of, the whole hokage situation to get sorted out, Naruto vs Sasuke fight, and whether or not the 5 nations will remain in an alliance or not. 40 chapters is not alot, that will barely be enough to cover all of that, plus more. No other relationships like SasuSaku or NaruHina will be able to get the amount of development NaruSaku and SasuKarin have. Especially NaruSaku, NaruHina can no longer compete, Naruto and Sakura have an entire series together plus the only canon movie RTN, even if Kishimoto devoted the next 40 chapters to just Hinata and Naruto it still won't be enough for them unless he does some bull*** a*spull deus ex machina
