Hey guys, this is just a theory, but don't you think Zoro will awake his Haki?
(this is now based on the Anime) but when he was fighting Mr.1, he said he had to cut through metal. He achieved it saying that he could hear everything around him breath. The ground, the rocks, the metal, the swords. This was what he used to cut through metal. He's been developing this ability, even though by sheer power, and aimming only for the consequences (cutting throught things), not actually the causes (trainning to hear the breath better, or use that breath to detect other, etc)...
Also it would be stupid to keep Zoro unable to fight Logia