With all these things, I don't why they were put/written in the first place, it just doesn't make any sense that any of Zoro's supposed parallels/relations to Ryuma ever came to fruition in Wano, not even the Shimotsuki thing. Either it's just bad or misleading writing that you just leave these plot lines open but then there is also the possibility that they are actually being saved for later for whatever reason.
If you look at it this way, Ryuma is a world legend (the reason for Wano and Samurais to be hyped, the other being Oden however Oden is nowhere near Ryuma). And the thing is that Wano was closed, it's walls raised around 800 years ago, IIRC. But somehow Ryuma still had to defend it from pirates and WG as Wano was known as the country of gold at that time. And the Wano of today is closed to most of the world, so probably for the Zoro surpassing Ryuma's legend, his feats need to be witnessed in a more open setting instead of current Wano and hence why the plot lines are still open.