I Think... inside that scroll is the technique to 'void' reaper death seal... so that sasuke be able to ask the previous hokages about the uchihas... and the strengths and weaknesses of madara.... In the previous chapter, sasuke was referring to madara... not shisui...
The scroll isn't a technique. It's information. It's likely information on where the sage/sons of the So6P are buried and how to contact them in the after life. We can pretty much establish that Orochimaru knows how to bridge the link between the living world and the spirit world.
'The one who knows everything' is obviously the So6P, though I can understand what Sasuke would want to also meet the sons: to understand where the curse of hatred came from.
If that statement is right, could it be possible that Naruto got the other half of the nine tails witch was sealed too now that the nine tails is friendly with Naruto he would probably love to have his full strength back.
We shall see, it's a possibility like any other possibilities.
The 9 tails is already fully powered. Even though a portion of it was sealed into Naruto at birth, it's power grew the entire time Naruto was alive, growing to full power at some point, which was why the seal kept weakening.
If oro and tobi know each other then it supports my theory on tobi being Izuna, in Obitos body.
1. Tobi is the one who started Akatsuki. Orochimaru was in Akatsuki as an original member. Of course they knew each other.
2. Obito's body was crushed to death by falling rocks. People need to understand that fact and let go of the 'Tobi=Obito' theories.
3. Tobi's body is made up of similar stuff to Zetsu. That's how he is able to grow limbs back and live for so long. I have no doubt that Tobi is Izuna, and some technique was used to transplant his soul into some body that Orochimaru helped make using Hashirama's DNA.