If Kishi has said the plot is linked to the Manga, and he is responsible for the story then IT IS Canon, It's Kishi's story, if he makes a certain pairing happen, it becomes Cacon, no matter how little it makes sense. that's what it means to be canon. When RtN was being released it was made perfectly clear it was Alternate History story, a What If, but it was made clear it was not part of Canon.
This one as sh*tty as it sounds is canon, the Main Antagonist being linked to the Hyuuga, makes sense if he is a decendant of the other brother, who the Hyuuga clan also appear to be decendants of, The only way anyone can argue it isn't is if Kishi had no involvement in the story, or comes out and says it's not the ending he's written, but everything point towards it being his story.
It's a good thing the Manga is ending next week, because after the movie is released no matter what the final pairing is Kishi could have lost a good portion of his reader base. No matter how he ends it, he's going to get a sh*tstorm of angry fans, and deservedly so, NaruHina, NaruSaku, SasuSaku, and SasuKari, which ever pairing doesn't happen will have reason to fell grieved, Kishi has deliberately strung all of them along, NaruSaku the most that pairings been hinted at since chapter 3 of the manga.
I honestly would not want to be working in the SJ mail room on the day after the movie is released, it will be full of mail from disgruntled fans who will feel Kishimoto dissapointed them. It's a lose lose situation, made worst by not even giving the fans confirmation in the manga but asking them to pay £10 for a ticket to be dissapointed.
I don't really know why I am caring soo much about this argument if it's canon or not, because, personally, I don't care if it is canon or not. And, frankly, you guys shouldn't either. The stories in Naruto, all the stories in all the media, could mean anything to anyone. The value shouldn't stem if they all exist in the same continuity timeline, it should always matters the quality of the manga, what individual people personally feel about them. We bash a lot on fillers, but, lets be honest, there are some good ones. Yet we automatically just ignore them for the simply fact of them being canon. Maybe that is why this whole discussion is bugging me, because we are taking this as canon material and should be taken into the same consideration as the manga. When in reality it doesn't have to. If the story doesn't seem interesting, if the spoilers and advertisement doesn't interest you, then the movie should have no value to you then, at least at's it current state.