So I've thought more about my answer and what bothers me about NS and trying to pinpoint when it died.... And that's just the thing. There isn't a single moment! There is no NS panel, no last connection between them, or last heartbreak. There is literally just nothing.
For me, I guess it would have been at the bitter end, with Sasuke's forehead tap and Hinata in the cemetery. It was just confirmation of the end. But not the death of NS. There just was no end to NS, along with no beginning of NS or no beginning of NH.
I realize the storyline was fleshed out in The Last and the novels, but you know, I don't really count those as canon to the story (the manga) because that Naruto is so vastly different from the original. Same with Sakura, Hinata and all the rest.
I wish i could go back and pinpoint a definitive panel between Naruto and Sakura when their romance was officially over...but there just wasn't one.
(In fact, their last panel together has Naruto thanking Sakura, which is used as 'I love you' throughout the whole manga. So even their last manga scene was an NS mixed message.)
I'm not arguing that NS wasn't canned for NH. It absolutely was. It's just...that all their development, all their mutual feelings were thrown out the window without a second glance. NS didn't end...they just went on like it never happened at all.
Another brilliant post from you tricksie, I agree with everything you said. We can only note that NaruSaku died technically by default, rather than have any sort of real moment where it ends.
While it would have been heartbreaking, seeing closure to their relationship would have been good, but there wasn't any. There was never a panel about Sakura's confession, or about what Naruto told Sai about loving her, or hell even just a talk about them staying friends.
Your second point, which I bolded, is another issue. All of these side projects, the new Bolt series, "The Last," other movies, other shows, in my view, they don't matter. The manga was the bedrock, the manga was the main vehicle for driving the story, the manga was the original source material. More or less, it feels as if the manga failed in telling a complete, well-rounded story at the end and needed a extra material for damage control.
Back to your first point, though, it raises an issue I've had with Naruto ever since it ended. That is that there weren't enough panels giving closure to any of the pairings really. We already discussed NaruSaku, but look at the canon couples.
NaruHina, strictly looking at the manga, Naruto and Hinata never really have a conversation about anything. I made another thread on this topic, that Kishi only portrayed this couple with "big moments," but never with anything simple or subtle. There was never any real interaction on a personal level, about sharing likes and dislikes or anything like that. Heck having a simple scene in the final chapter where Naruto and Hinata go have ramen together after the war would have gone a long way. Instead, it just happens, and that's it. The epilogue doesn't even show Naruto with his wife.
SasuSaku, meanwhile, had some more panels, but as previously stated, everything just happened by default. Neither Sasuke or Sakura had any panels showing growth in their characters, instead Sasuke remained an kitten, Sakura reverted back to a fangirl and the two just had a sort of mutual agreement that they would be a couple.
Looking back, I realize full well that this was a shonen manga and not a romantic one. I get it. However, writing dialogue that advances and explores characters and their relationships isn't foreign to shonen or action oriented series. It's writing 101.