I kinda agree that sealing Kaguya seemed to be too easy.
However, there are rumors that "The New Era" project is not just about the upcoming movie but also about Naruto Part 3 (All characters will be young-adults and Kakashi will be the 6th Hokage)...That's why Kishi is rushing to end this arc. And if this come true, I don't think we will see Naruto and Sasuke fight soon, and I think this arc will end around chapter 700, then Naruto Part 3 start.