I know what That Jutsu is :)
While naruto was training with jiriaya... jiraiya stated that naruto was the only one with enough chakra to master That jutsu which is the jutsu that even the Fourth Hokage couldn't master...
Before the timeskip Naruto and Sasuke where equal. But after sasuke was way stronger than naruto and we all know that nobody trains harder than Naruto and learns a tech as fast as him so i believe thats because Jiraiya spent most of his time trying to teach naruto how to control the kyuubi and how to one day perform that jutsu
That Jutsu is the reaper death seal
I believe Minato created the reaper death seal to protect the village from major threats but the problem was that it would kill and suck him in as well (thats why it is incomplete) .. I believe that minato created it and also developed the jutsu with the third hokage . And i am sure minato thought he would have been able to master the reaper death seal before he actually used it. My point is that naruto will learn or already know the reaper death seal and he will be able to perform a complete version of that jutsu and actually be able to pull souls out as well as seal them away without getting his soul trapped for eternity.
And those that say no it cant happen because they said jinchurikis cant use it... you tell me how many jinchurikis even tried RDS lol i believe they said that because the body and chakra of a jinchuriki is imbalanced and unstable because normal jinchurikis dont get along with their beast and the beast usually hate's its host and wants to kill them... BUT Naruto could pull the jutsu off because he is one with the kyuubi now