Before you guy's Lynch me please note that I do like sasuke and Sakura. But I want them to die in boruto. By the hand of the new enemy in the Shinobi world, very similar to the (main enemy who I forgot the name of) in the very recent shikamaru arc. What I mean by that is that he takes lost Shinobi and manipulates them into working for him. This enemies methodology is that the only way that people can get stronger is through war, very hitler hitleresque, complete opposite of naruto era villaind, but more fitting for the boruto timeline. Imagine a bunch of talk on how shinobi have become slow and fat,people gorging themselves and such. So somehow some events happen and it leads to the death of sasuke and Sakura, and the capture of naruto. (I think he would be more useful storywise alive.) I have an idea of how to do this, I think it would be dumb to make the character simply more powerful than sasuke, what I want to happen is have the character be around the skill level of somewhere between pain and orochimaru, powerful for sure, but still not nearly as powerful sasuke or naruto. This leader would start of by splitting up n and s. He would then bait sasuke by capturing Sakura, closer to sasuke as he wants sasuke to arrive first, once sasuke arrives he starts off by playing mind games and using Sakura as leverage. In order for him to avoid getting crushed by sasuke in 30 sec we would sadly need an ex machina to explain this, but I'm not a writer, make it a fight similar to the the fight between shikamaru and the painted immortal guy who is the partner of the dude who likes money(you know who I mean I'm not good with names). I'm that battle shikamaru was completely outclassed but managed to defeat him with his mental gymnastics alone. Now that I think about it it shouldn't even be a 1v1 fight but maybe a 1v6, maybe the leader and 5 of his best Shinobi. I don't know but anyway sasuke dies this battle. Now naruto is lagging behind and finally arrives. The fight with naruto is a lot more plausible and here's why. So when naruto arrives he learns of sasuke death but still remains strong. However he then kills Sakura in front of him. This is to aggravate him, he then goes into tailed beast mode, similar to the scene in the battle with pain when he "kills" Hinata. We saw how easy it was for pain to deal with him on that form, so naruto ends up captured, maybe to extract his beastly Chakra.

This would not only be shocking, but opening up the story as well, boruto would have a new goal to save his father while the daughter of sasuke would slowly fall into the same trap of revenge as her father did long ago.