Board Thread:Theories and Speculation/@comment-33953813-20171226015659/@comment-734582-20180103213552

LovelyFox wrote: Madara was caught off-guard by BZ and also he got weaker after using IT at some degree (bags under his eyes after IT clearly indicate that). Doesn't change the fact that he was still insanely powerful. BZ was able to subdue both Naruto and Sasuke for a while, who were together more or less equivalent to TTJ DR Madara. So yea, indication is that Black Zetsu could also control Obito.

Besides, it's about what Madara would've planned, not about what BZ actually intended. BZ was fast enough to outplay Minato, and stealthy enough to mislead and backstab Madara. Obito would not have much choice in this whole affair, if BZ would chose to supplant Obito with Madara.