Following the recent update we got about the Boruto X Naruto crossover, We've received new details about the storyline and they may not be what you expected.
According to the summary, episode 128 Boruto and Sasuke will travel back to the past in pursuit of Urashiki with the hopes of stopping his evil plan to kill young and weak Naruto and ultimately putting an end to the Otsutsuki once and for all.
Urashiki has been determined to suck up all the Bijuu chakra he can, but he cannot get to the Nine-Tails thanks to Naruto. Since Urashiki cannot beat the Hokage as an adult, he plans to go to the past to kill Naruto as a child, but Sasuke will not allow that.
Sasuke is trying to keep a low profile and not raise suspicion or come in contact with his old teammates but things don't always go according to plan especially when you're paired up with someone like Boruto.
Of course, things go haywire when a certain knucklehead ninja shows up. A young, genin version of Naruto will appear before Boruto even though the latter was trying to avoid such contact.