I agree with most of your points but between luffy finally going up against a yonko, all the backstory with momo and oden and the training the focus in wano wasn't on zoro there was just too much else going on. There were a few hints dropped about zoros ties to wano but I'm guessing that oda is saving the big reveals and focus on zoro for when he finally fights mihawk again and possibly for when we meet whoever helped shimotsuki kozaburo leave wano, I have suspicions that dragon was somehow involved, he may have helped them escape wano as refugees when kaido took over. I'm also expecting zoro to get another sword made by shimotsuki kozaburo to replace his kitetsu so that all 3 of his swords are made by the same person.
As far as the whole black blade thing, I'm guessing it just happens after he has spent enough time in battle infusing them with conquers haki the way he did when he cut kaido so it will eventually happen as he has more battles of that level.