TBH We are more on the same page than I thought we were. Though Naruto meeting the So6P will definitely happen two facts kind go against it.
1# Hinata asking Neji to protect Naruto ( makes me think Naruto may see Neji in the afterlife)
2# Gaara knows what he is doing (its no mystery anymore that what Kurama told Gaara was a way to save Naruto) Where ever they are headed its gonna be a planned effort. Gaara wouldn't know about the Sage cuz I don't even think the Kyuubi knows that the Sage will make a reappearance
Finally, Sasuke will TNJ Madara. I don't think it will work, but it will possibly get Madz to slip up and give Sasuke an opportunity for Hashi's jutsu.
One last question: What's your opinion on how Madara survived. I am kinda partial to genjutsu
You do have a good point about Neji. I could see Naruto meeting Neji in the afterlife. We kind of saw a Naruto, that (once again..) lost will to live, since he lost Kurama. He saw all the hard effort he used to free the bijuus vanish, and so it is no wonder, if he just gave up. Neji could be the one to kick his ass back in motion. But I could also see a possibility for Jiraya to make an appearance in the afterlife, as he has already met his mother in another way, though this would go against my theory of how this whole afterlife thing makes sense.
I do think Kurama knows something, because the sage said, that all the bijuus would once be together again (I understood that as they would all be sealed to the same person). They all now feel, that this person has to be Naruto. Of course it would seem strange, if he knew it would be possible for Naruto to meet the SO6P, but I do think he knows, that Naruto can gain some of his powers that way.
Whether, what Kurama told Gaara is directly related to
that, or it mainly focuses on saving his life, I don't know.
Regarding Madara's survival..
Hmm, at first I was thinking genjutsu due to the signs with the thunder and the moon. The only moment where Hashirama was distracted, was due to that.
Then theories about this body splitting technique (the one Muu used) started to flourish, but I never really like them, because Hashirama has sage mode, and he can't possibly be so bad at sensing chakra, that he wouldn't realise something like that. Unless Madara had used that jutsu before the battle even started, which could somewhat make his current power-level make sense. But that would raise a lot of questions, such as
why not just kill Hashirama and everyone else using the Kuybi and other tailed beasts, he could quickly gather.
Also it does not seem possible, that he actually died and was later revived by someone, because of the conversation Madara had with Kabuto after smashing the boulders over Gaara, Onoki, and co.
So I guess I'm still down to genjutsu, not that I like it, in fact I dislike it very much, but it's the only theory I find plausible at the moment. Tbh, I doubt it so much, that I think he survived in a manner, which we cannot predict, because it either involves a jutsu, which is unknown to us, or it involves using a jutsu in a manner, which we did not think, would be possible.