As of now, Naruto and Sasuke haven't died in the Boruto manga. Their characters continue to play significant roles and contribute to the story's development.
Sasuke and Naruto were both very powerful characters in Naruto, but it was difficult to determine who was more powerful in the manga. Because their abilities and backgrounds were very strong, they had made great achievements in different fields.
Sasuke was a genius ninja of the Uchiha clan. He had unparalleled speed and strength, as well as powerful eye techniques. He often used various powerful ninjutsu and skills in battle, such as Unlimited Moon Reading, Susanoku, and so on. He had defeated many powerful enemies in battle, including Naruto's father and Naruto himself.
Naruto was the genius ninja of the Uzumaki clan. He had a strong vitality and powerful ninjutsu ability. His commonly used ninjutsu included the Spiral Pill, Shadow Clone Technique, Tail Beast Jade, and so on. He often used various techniques and strategies to defeat his enemies in battle. He had fought fiercely with Sasuke in many battles and almost defeated Sasuke at one point.
In the manga's plot, Sasuke and Naruto both showed very strong abilities and strength, so it was difficult to determine who was stronger. Each of them had great potential and strength in different fields, so if they fought, it might be very intense and exciting.
The Naruto manga continues well beyond Sasuke's departure. It covers many significant events and character arcs that shape the overall conclusion of the series. Sasuke's leaving is just one part of the larger narrative.
It might be for Naruto's own good. Sasuke may believe that Naruto is on a dangerous path that will lead to his downfall. So he captures him to keep him from making bad decisions, like sacrificing himself for the village or something similar. He wants to save Naruto from himself in a sense.
In some fanfictions, Naruto might reject Sasuke because of Sasuke's continuous pursuit of power in a way that endangers others. Naruto, who values friendship and the safety of the village, could see this as a betrayal of their shared values.
Naruto might protect Sasuke by using his physical strength. He's got those powerful jutsus like the Rasengan. If any enemy comes near Sasuke, Naruto can just blast them away with his attacks.