Potential Successors to Naruto Uzumaki: Sasuke Uchiha, Hinata Hyuga, Sakura Haruno If Naruto were to die prematurely, his peers Sasuke, Hinata, and Sakura would be likely candidates to inherit the Nine-Tails. Sasuke's power could easily overpower and control it, driven by revenge and protection.
Sakura's close relationship to Naruto and her husband Sasuke would also make her a potential successor.
Hinata Hyuga, despite being ranked lower in power, possesses innate talent and the Byakugan bloodline. Her love for Naruto could lead her to inherit the Nine-Tails or awaken the Rinnegan for vengeance.
Successors to Boruto Uzumaki: Kawaki, Himawari, Mitsuki, Sarada If Naruto and many peers died, Naruto's disciple Mitsuki and his children Boruto and Himawari would be the likely successors.
Mitsuki already has a close bond with Naruto and has learned from him. It would be fitting for Mitsuki to inherit the Nine-Tails. Boruto and Himawari also have a good chance, but Boruto's rebellious nature may lead him to choose Sasuke's Rinnegan. Himawari has expressed a desire to become Hokage and greatly admires her father. Sarada Uchiha, Sasuke's daughter, could also inherit the Nine-Tails.
No Successor, Regaining Freedom for the Nine-Tails Since the Fourth Great Ninja War, Tailed Beasts have had the freedom to choose their own paths. If Naruto were to die, only those recognized by the Nine-Tails could inherit it, otherwise, it would be forcibly sealed and used. If the Nine-Tails did not want a successor, it could regain its freedom upon revival, but there is still a chance of it being controlled again.