Taking Kurama out of the equation changes everything as he learned all of his major techs by abusing the 'natural mixing of chakra and greater stamina and the ability to spring back on ones feet' - confirmed by Kakashi a few times. Once you take that out, he's left with good chakra and very little talent. I am sorry, but making 1000 clones to create a tech by greedily amassing their experience isn't talent. Not by any stretch of imagination.
He perfected - in his way anyway - the Rasengan and KB because Kurama allowed him to spring back on his feat without any repercussions. Kakashi confirms it, that the more clones you make, the more exhaustion is added to the over all pakage as well. He also leanred Sage Mode by divinding up the time. So, let's throw this 'talent' notion out of the park.
Just because Minato learned the seals doesn't mean Naruto can. This analogy doesn't even make any sense, as Minato is a 'once in a decade' prodigy. Naruto is an idiot who was shown to be incapable of grasping basic concepts and is taunted on the same front by just about everyone. Sure, he has had his 'smart' moments, but that is something almost every character managed.
Heck, the guy had no clue that he was amassing the Bunshins experience, when he had literally read the scroll himself. He was still incapable of forming a one-hand complete Rasangan-tech at the end despite possessing countless decades worth of experince under his belt. If that doesn't scream talentless, then I don't know what does.
Naruto learning some complicated seals is fiction. His entire progress proves that he won't be able to. I can see him learning Rasangan by the time he reaches adulthood, as without Kurama that cut-short time for learning techs tricks isn't happening. FRS? Yeah, I don't think so. Sage Mode? An imperfect one is all I will give him.
What else? He'll he mid-Jounin level without Kurama, at most. People forget, that Kurama played an integral part in his recovery from clones and to get a hang of them in the first place. Without Kurama, Naruto would be pretty pedestrain, given the fact that he doesn't even possess the pure Uzumaki genes, proven by Kabuto.