Zoro will get flipped, but won't be controlled by Imu. He'll get the powers of a demon without the drawbacks. In an epic doublepage he'll mirror Usopp's line against Perona and say: "I am always a Demon".
That will prove to be the key to defeating Imu, as he'll think Zoro is a black piece due to being flipped, but he'll be acting as a white piece and pteventing others from flipping instead. That will prove to be what was needed all along, this one piece. Which Luffy has had from the very beginning.