Proof please?
I'd hate that. Some random strong fodder without any ties to the main plot for 400+ chapters suddenly being the one? Maybe if it was a quick epilogue where Naruto is the Hokage, facing said enemy, saying whatever cool phrase and smiling before cutting to the end.
It'd be quite the twist if the Juubi has been manipulating Madara from the moon like a satellite, all this time after his loss to Harashima. He planned to use Madara as his host/agent to slowly put in place a plan where he is reunited as full. Madara thinks he is doing it for his own gaom but the Juubi will end releasing all Hell if he goes that far. Well it's a theory.