it's like saying "kakashi and rin would have happened". why even ask for that? if not for obito kakashi would have let rin die...
kishimoto and his brother were probably close so he wanted to keep the team the way it was in the story. even in dragon quest/hunterxhunter/o-parts hunter they all have a character kind of like sasuke
I'd make the argument that Seishi kept Ruby Crescent (the heroine) a core integral component to the narrative of O-Parts Hunter, and specifically to Jio Freed since the first chapter of the series all the way to the end. You could just tell inseparable Seishi made Jio and Ruby which really shows. The final chapter cover also speaks a lot on that front too.
Masashi really needed the same touch that Seishi had when it came to developing his female characters and of course the romance aspect of it for Naruto and Sakura.
I do wish so much that we got the same level of love and care for NaruSaku especially in the later half of Part 2 without Masashi throwing a bone to get the fandoms to wag their tails... like "OMG could it be? Could it be?" and I'm just like thinking.... as an aspiring writer..... this is not how to win over your readers when it comes to developing romance between two characters.
I know the argument a lot of people make is "Well Naruto isn't a romance therefore it's fine we didn't get a lot of focus..." that has always been such a poor excuse I've heard time and time again.
Which, I'm gonna say this.... if romance isn't gonna be a super integral piece to the narrative of your story.... which is totally fine because any writer has the freedom to do that, but... here's my advice.... Don't just fool around with your readers about which couple will be canon.....
If you as the writer already know from the conception of your story that this couple is going to be canon then just focus on developing that pairing as you are telling the story you've created.
That is definitely the #1 thing Masashi didn't understand when it came to Naruto.