I'll have to respectfully disagree.
Kishimoto has added new emphasis to the elder and younger son parallel. Based on that I'm now questioning whether or not Sasuke will obtain the Rinnegan/Mokuton. Kishimoto had many believing that Naruto would be the reincarnation of the Sage, but instead we've learned that he is the reincarnation of Ashura (the younger son).
I believe that Kishimoto may have simply misdirected readers with Kabuto pumping Hashirama cells into Sasuke. It could be that Kabuto is somehow using those cells strictly as a means of healing Sasuke.
If that happens, I wouldn't mind it.