"This is a technique to bind him in response to that” (Referencing the Senjutsu Madara stole)
So clearly, this technique (not DNA) that Hashirama gave Sasuke will react to Senjutsu. Now… who around Sasuke has an affinity/affiliation to Senjutsu naturally, and has given him his flesh before… that’s right! Juugo. This is another case where Juugo will need to transfer his life force via his flesh (like in the battle against Kirabi) in order to help/save Sasuke, who is in a dire situation.
This is where I believe the catalytic nature of Hashirama’s technique will come in. Juugo’s flesh (which will now be in more abundance within Sasuke) will react to Hashirama’s technique (chakra) and Sasuke will be able to balance nature energy in order to achieve Sennin Modo (the mode will most likely be a more complete version of the one granted at Ryuchido as Kabuto had many modifications done to his body that were lacking in human nature).
The normal effects will transpire (all the abilities and benefits) but once Sasuke uses his Eien No Mangekyou, it will transform in to the ESD, and in conjunction with the markings around his eyes, he will be a near spitting image of the Elder son, nigh the long wavy hair.
Not only is this extremely beneficial for Sasuke, it adheres to the current situation. Madara as a Jinchuriki now only has one weakness; Senjutsu. And this is why Sasuke will need Senjutsu to combat Madara.
The particular benefactors regarding the abilities it grants are still outstanding. But Sasuke will basically be the peak of the Yin (Elder Son) and will have Sennin Modo to boost everything in power, size, efficiency etc. Being the peak of Yin will most likely grant Sasuke massive boosts to every Genjutsu he uses. The prospect of time manipulation that I’ve talked about before may become a reality, depending on the nature of the ESD. And in all actuality, with boosts from Sennin Modo and being the peak of Yin chakra, Sasuke’s Perfect Susano’o will most likely supersede Madara’s in size.