Pretty strong thread here the point about nagato and the chakra rods isn't that good but besides that makes sense. Also as when orochimaru was sealed in assume or put the curse seal on say anko his essence was pressent
I seriously doubt that the Juubi just remembered Rikudou in Naruto, you can clearly see that the Juubi sensed the Bijuus inside Naruto (Hachibi was not present) so it only stands to reason that Juubi also felt Rikudou's chakra inside Naruto which is the following panel.
I agree, the SO6P story will be told soon. My guess is once he retrieves the tailed beasts like he said he would, or while trying to save them.
By manifest do you mean something exactly like Minato and Kushina meeting Naruto? I just don't see how that could happen unless every bijuu possesses a part of the sage himself, even then there was no sealing, just energy/chakra donating. Just seems like a stretch. None of the bijuu have mentioned anything and I'd assume they would know something.
Nice theory regardless as usual Derp!
(Awesome and hilarious signature by the way)