What are some things Kishi could've done to keep Sakura popular and not allow her to lose her status to Hinata (besides getting rid of Hinata of course)?
What are some of the things Masashi could have done to make Sakura popular and be viable as a main character? Understand why Sakura isn't popular in the first place and work on the things that he could change, and not worry over the things he can't.
How much of that he could influence, I don't know, but Sakura's popularity as a main character took near unrecoverable hits with less than 107 chapters under the series belt. 14th is NOT popular, particularly if you're supposed to be one of the MAIN CHARACTERS. And worse, this is AFTER we have revealed stuff about Sakura, demonstrated her kind and caring nature, her ingenuity at work, and her similarities to Naruto. All that stuff out about Sakura, and the readers prefered, in order, a sadistic super pervert (Jiraiya, 10th - 503 votes), a super-androgynous character that died like 80 chapters ago (Haku, 11th - 434 votes), a picture of an unnamed Hokage (The Fourth Hokage/Minato, 12th - 402 votes), and the clear-cut mustache-twirling heel for Naruto to righteously thwart (Neji, 13th - 396 votes) over one of our MAIN characters (Sakura, 14th - 359 votes).
At this point, who gives a flying fig about Hinata's popularity? The trouble spot is Sakura and her consistent low showings in the character polls, given her status as a main character. First seven polls, she comes in 5th, 14th, 9th, 10th, 8th, 12th, and 12th (tying with SAI, whom I understand to be pretty unpopular character in Japan -- NOT good). Even more damning -- after the second character poll, the less there is of Sakura in the manga, the higher her positioning is. Whenever she becomes more relevant, and gets more screentime, though...
As one saying goes, "Once is a coincidence; twice is a pattern."
If I was penning Naruto, and Sakura was ever meant to be his love interest, I sure as hell would be reconsidering that plan, let me tell you, because those polls, with the first six appearing to have been taken yearly, tells me that the readers don't like Sakura very much. Not as a main character, at any rate.
So, how does one change all that? Personally, I don't think you could, given the reader response. Not without starting over. Sakura got power-ups galore -- readers don't seem to care. Sakura's "confession" pissed off pretty much everyone, so romance redirection isn't likely going to win them over, either. And while you can drag a horse to water, you can't make him drink, so shoving her into the faces of a readership that doesn't seem to care about her is likely going to make them even more resistant, and Lord knows, no one wants to drive off their reading base.
So, my answer is... rewrite her entirely. The Sakura developed is not going to magically become well-loved if you gave her cool powers, or if she gives birth to all one thousand of Naruto's babies, or if the series was retitled SAKURA. Her character is faulty, and while some would say it's because of her Sasuke-centric feelings (which, given how she and Sasuke came about, is fairly justified), I would say it's because she doesn't have a future she identifies with that also ties into being a main character like everyone else. Naruto dreams of becoming Hokage so people will give him proper recognition; Sasuke dreams of killing his brother and restoring his family line; Sakura dreams of Sasuke and... that's about it. A main character absolutely needs a driving goal, force, or objective that propels him or her forward, a task that the character must absolutely do and succeed at or die trying, and that's something Sakura is wholly without.
By the time she does get one, it's already too late to utilize it properly -- we just wasted 270+ chapters of development, and now, it's going to be a tougher sell getting people to like the NEW and IMPROVED Sakura with so much baggage attached to her current character.
So, instead, she would need to start with some kind of driving goal that makes her a main character -- for example, let's say Sakura wants to be a ninja rock star. =BAM= Now the world is going to open up for our intrepid wannabe future ninja rock star. The obstacles she'll face, the tasks she'll have to overcome, the roles she'll assume, the people that'll cheer her on as well as those she'll have to battle in order to bring about her own dream, presuming that she CAN bring about those dreams. Everything that will culminate into answering the one question that we MUST know -- does she succeed, or does she fail? How does it go for our main charactetr and her dream?
In the end, I can but theorize why the Japanese readers aren't down with Sakura. In my opinion, though, Sakura doesn't have something to make her interesting, and that something is a dream to follow, a passion and dedication to something that not easy to obtain. Beccause of that lack of a dream, it's going to much harder for readers to sympathize with her than say Hinata, a introvert, timid girl who might as well be invisble to the guy she likes but dreams of someday being strong and courageous enough (and worthy in some cases) to walk beside that guy. Or Shikamaru, a slacker who dreams of having a peaceful, boring life, a dream which eventually gets dashed in favor of a dream where he serves as protector of Konoha's future, the children of both his sensei and his own.
Persona 5 hype 
I want the compliment of James Bond! <3
