Where is the other half of the nine tails? Sealed by Minato, is it available will it make a difference in fighting the Juubi?
Minato sealed half of Kurama with him, to prevent future problems.
He only seal the other half (% unknown) in Naruto, hoping Naruto can use.
Next issue is weird. Kushina help Naruto to take control of Kurama,
and Naruto extract portion (how small or big) separately from Kurama,
for himself to use,if nec. I think Naruto is using now bec he is still not tired.
So there were 3 portions; in Minato, Naruto and Kurama.
Juubi look like concentrated all the sealed bijuu in him, 7x bijuu power.
Issue is if Kurama go into sage mode to generate more chakra,
then can Juubi also do it likewise, ...Naruto world ending.......