Kishimoto is pretty good at throwing plot twists into his stories. Usually things aren't the most obvious, yet also not the most obscene at the same time either. With the unfolding of the past, a lot of speculations by readers are either being proven or debunked depending on what actually does happen.
I don't think Naruto has any lineage of the sage of 6 paths. It's probably Nagato alone that is the inheritor of those eyes and skills. Although Naruto is a sage, it's through his pact with the toads, so his senjutsu are of a different technique than that of the Sage of 6 paths. Although I would say that Kushina's sealing jutsu of her clan are among some of the jutsu directly derived from that of the sage of 6 paths, such as that of the eye techniques of the Uchiha and the Hyuuga.
buuut, we'll see in a few days how all of this stuff fits together, or perhaps a few weeks.
Minato and Kushina probably did the ultimate sacrifice by sealing parts of themselves and the fox inside Naruto and in some way also sealing away Madara for some time to keep him away from the fox.