Well I think Neji would definitely not be too happy about that xD but then at the same time he might realize that maybe he was just wrong about the whole "destiny" idealism and become a di*k again xD
Kabuto...hmm...not sure, Kabuto doesn't really know Naruto on a personal level, but still he'd probably be like "Screw that.Madara, you can handle Naruto on your own" cuz Kabuto's just like that.
Iruka would probably take Naruto out for some ramen (again) and he'd probably say something like "I knew that there was some resemblance there..." and then he'd probably start talking about how Naruto has grown so much since before he was a ninja and stuff, etc.
Not sure that FTGT could even be a Kekkai Genkai since (as far as we know) Minato created it, and if it was KG then Minato probably would have had it from the start, and so would Naruto..though there are a few alternative theories to ftgt being a Kekkai Genkai..Like with some dieases, etc. it could come out when he's done with adolescence or something.Either that or Naruto might have to just master his other priorities first (Nine-Tails Mastery, etc.) If he hasn't already mastered the Nine-Tails, and so far by my knowledge he hasn't completely mastered it, but still has better control over it.
Kinda just went on a wall-of-text there lol

oh well but Naruto inheriting or re-developing the ftgt would be amazing and Naruto would become just that more awesome.