I like the prediction, it isnt' bad. I think it would be more believable if instead of hashirama talking to Madara in the after life, it would be Madaras brothers and family.
I do believe that Sasuke will cancel the genjustu using his rinnegan, ultimately losing it and keeping his (or rather, itachi's implanted) eyes.
and since Naruto cant keep his powers and has the largest chakra reserves, i believe he will "share" the sages remaining chakra with those across the lands so they can all survive from turning into white zetsus. After Kaguya made the giant guodama using everyones chakra, we aren't quite sure how near death they are.
SO if Sasuke cancels the genjustu, it only makes sense for Naruto (whom has the largest chakra reserves in the entire manga, even beating hashirama) to use the last remaining power of the Sage by sharing the chakra and keeping everyone alive. Which was intended by Sage the whole time, chakra was meant to be "shared" but instead gave birth to Ninjutsu (i forget what his way was called.)
Off topic, but i was hoping madara was gonna make a come back and we fans would have gotten a PROPER ending, instead of the shittiest arc and villian (especially for a female..ugh)
This whole ending feels rushed for release so that they can make money off of this last movie which is also supposed to show what happens after the ending of the manga following the war.