Shion was interesting as a concept, being a priestess and what not. The movie was not the best, but her interactions with Naruto was the strongest point, especially when finding something in common with their childhood. However, I don't think she's to blame for this current mess. If she was that well received, they would have just pulled a DragonBall Super and made her canon.
Fu sounded like she had a lot of potential, which is a huge problem for the current story. These jinchuriki characters had so much potential, but Kishimoto only did things with THREE of them.
Can you think of a next gen story that's actually good?
Batman Beyond is one. They made Terry McGhinnis a different sort of Batman from Bruce Wayne, and they could have easily given him carbon copies of Bruce's rogues gallery, but they didn't. Even when the old Batman villains came back, it wasn't in the way you would expect. They even did something neat with introducing Terry to his current Justice League.
And while this has been debated, in my opinion revealing Terry was Bruce's son wasn't necessarily a bad thing. He grew up to be an entirely different person without having to rely on Bruce's shadow.
Another is Legend of Korra. They made sure Aang was dead, and his son was already grown (sorry Bumi and Kya, CHILDREN). Korra was definitely her own person and not a carbon copy of Aang in the slightest. I could go on, but whatever you think of the series, the creators did their utmost best to differentiate the new series from the previous and didn't have to rely on the old one. For that at least they should be praised.
The Redwall books are somewhat along those lines, albeit they span over several generations.
You could say the Power Rangers/Super Sentai are also similar. Ever since the 2nd half of Turbo, the cast of Power Rangers changes each season, even though the old rangers will pop up every now and again.
That's all I got really. The problem with Boruto is that it relies on the son of the previous protagonist, and it automatically puts him between a rock and a hard place. There's this expectation for him to be like his father, but that will just make him a carbon copy. And when they try to differentiate him from his dad, he feels like a betrayal of everything Naruto was.
It also doesn't help that they're repeating EVERYTHING about Naruto with Boruto down to the letter (team, betrayals, love? etc) We keep getting more or less the same villains and we're stuck in the same place, so it already feels like "been there done that".
This is why you should never make series about SONS/DAUGHTERS. People expect them to behave the same, and you're just stuck telling the same story.