Actually, that last cover is depicting Naruto and Sasuke as Fūjin and Raijin, the Shinto gods of wind and lighting. It really doesn't have anything to do with Sage Mode.
I highly doubt that Kabuto gave Sasuke the other DNA he possessed. He was never stated to have integrated Hashirama's cells with himself (no Mokuton in his fight against Itachi/Sasuke), and only Hashirama's cells were referenced when Kabuto was healing him.
Sasuke, having received chakra from Hagoromo himself, does have a connection to senjutsu since Hagoromo's is derived from Kaguya, and thereby the Juubi, which is made up of natural energy, hence why he was able to perceive Naruto's absorption of Natural Energy at the Valley of the End. However, it isn't as powerful as the Six Paths Senjutsu possessed by Madara, Obito, and Naruto.