Another circle of "what if..." here. Let's just go with logic and facts:
NaruSaku in manga:
- Huge amount of development (from chapter 3 in part 1 to Naruto's answer to Minato about Sakura's status to him)
- Naruto's statement to Sai about his feelings for Sakura and POAL to deal with.
- Sakura's change of heart through part 2, noticeable to many other characters (Yamato, Kakashi)
- Massive parallels with Minato x Kushina and Naruto x Sakura
NaruHina in manga:
- None of moments as development from both sides (only Hinata's)
- They barely talked to each other in whole manga.
- None of parallels to anyone
NaruSaku in RtN:
- Naruto and Sakura - main characters to plot.
- Plenty of parallels to another MinaKushi
- Kishi involved
NaruHina in RtN:
- Is there been any scene where Naruto and Hinata where 1x1? 
Some facts that Kishimoto said by himself:
- He wanted to make Sakura more of a heroine.
- He wanted to draw Naruto as father
- He wanted to end manga with conclusive ending
Problems/Questions to NS becoming canon:
- Sakura's final change of heart from Sasuke to Naruto.
- When exactly and how will it happen?
Problems to NH becoming canon:
- 90% of this post
Problems of "The Last" movie:
- Reason for 2 years timeskip?
- Some fillerish flashback about child Naruto x Hinata
- SP try hard force for a Hinata as heroine (not really a problem, its just triggering some people with "NH is canon!!!" thing)
- Almost none information about what happend to almost all characters during this 2 years (especially Naruto/Sakura/Sasuke)
- Position of this movie in whole timeline of story. (?)
If NS become canon to a main story:
Fair enough to a character that are involved to it.
Not contradict to a logical ending/main story telling.
Pretty big development in almost 700
If NH become canon to a main story:
Not fair to one of involved charactert in this pair.
Break main logic of a Hero's character.
Makes a lot of story moments - illogical.
Contradict the general logic of whole story.
None of development in canon story.
Open questions:
- Will Kishimoto end manga with conclusive end?
- Will Kishimoto end this whole pairing subplot?
So if you can read this and still tell me about 50/50 to NH becoming canon, and don't tell my WHY exactly, then you are just some horrible horrible person
or just troll 