IMO Hashirama gave Sasuke a jutsu that will cause Madara to lose control of his Hashi cells. If that happens then Madara won't be able to retain the Juubi
So....that still hasn't been revealed yet. What the hell did he give to Sasuke? Senju DNA, so he can summon the presence of the Sage of the Six Paths and awaken the Rinnegan?
Then again, Hashirama would need knowledge of the SO6P and Rinnegan for him to even consider the above