Naruto mastered the most advanced shape manipulation technique rasengan in no time being 12 years old, with Kurama altering his chakra control.
And Naruto is the child of the prophecy, so even if he has not Kurama sealed in him from birth, he would still befriend him and the 8 other beasts, as the prophecy stated.
So without Kurama Naruto would just be more precocious to attain his full power, as his chakra control would allow him to learn faster and better.
Without Kurama sealed in his body from birth:
-Naruto would only need one hour to master rasengan,
-a day for perfect sage mode fused with Ma and Pa and Myojinmon and many summonings,
-he would have mastered Minato's shunshin in no time as Minato would probably still be alive,
-same for the rasenshuriken,
-then the mastery of the 5 elements,
-being a master healer,
-the Uzumaki sealing jutsu and chains as his mother would be alive,
-Ashura's powers (ninshuu and Yang mastery),
-finally with ninshuu he would befriend the 9 beasts and awaken 6 paths sage mode and many KKG...
13 years old Naruto would be kage level without Kurama sealed in his body from birth.