The shinobi war was lost, Sasuke died but before dying he gave Naruto the Rinne Sharingan asking to preserve his legacy, later Naruto also dies, but Sakura brings him back to life giving her own (Chio's jutsu) in return. In a final attempt to kill Madara, they clash in battle. As a result of the battle, the space-time continuum was torn apart. It is unknown if Naruto killed Madara or not. From this spatial anomaly, Naruto enters the Remnant World (RWBY)
IMPORTANT NOTES:
*Naruto killed people and was a little more serious,but still friendly and cheerful with friends
*Naruto does not know how to use the Rinne Sharingan, but he can learn since he also has the chakra of the sage of the six paths like Sasuke
*Naruto knows fuuton ninjutsu well and can learn the rest of the elements. And NO! Naruto won't only use the Rasengan!
*Naruto loved Sakura and her death was the final straw. And yes, Sakura hasn't been chasing Sasuke since she started studying with Tsunade and she has real feelings for Naruto. NO HINATA! she is too annoying and Naruto himself does not feel anything for her
*Naruto has lost all of his friends and teachers, so he looks more like Kakashi who lost Obito and Rin.
*If you want, you can take Naruto to the world of Fate (stay night / apocrypha), My Hero Academy, DxD or whatever you want.