First, my thoughts drift to Oden’s Wife. I don’t think we have seen the last of her because it seems like a waste of a character and Oda isn’t one to waste.
Plus I’m sure she will come back into the spot light because her face hasn’t been shown so a reveal is coming. Now If I read it correctly, she’s from the far far past and only stopped traveling In Oden’s period. My guess is she may even be from Ryuma’s period or right after where everyone knows who the King Ryuma was.
Now I don’t see her hurling Ryuma into the future like she did with the samurai because it would outshine Zoro a bit and we don’t need two samurai, but maybe she will appear at some point in front of Zoro and confuse the two. That or realize he is the descendent of Ryuma. Zoro, for whatever reason, has stayed out of eyesight of everyone, such as when Kaido came, he didn’t get to see Zoro and I feel that is for a reason concerning his looking identical to Ryuma, but that is for another theory.
My personal opinion is that Zoro’s parents left Wano when Kaido came into power there 20 some years ago. They were probably samurai or nobles or something and fled. I don’t think Zoro’s parents would look identical to Zoro otherwise the samurai would have instantly recognized Zoro. They fled to the East Blue 20-21 years ago with a baby Zoro. They hide their identities because if people knew they were samurai or from Wano, Kaido would have chased them to the East Blue, so they never told anyone, not even Zoro. Hence Zoro has no knowledge of the samurai or Wano. The timing fits it perfect. Zoro is 21 years old now, they left when Zoro was 1.
Luffy got a flashback arc with Sabo and Ace as kids. Sanji got one with the Germa. I highly doubt Oda will leave Zoro to just appear out of no where at 10 and train at a Dojo. So I would Say Zoro is going to get an amazing story, he was separated from the crew for a reason. Anyways my main point is that Ryuma will probably get some flash backs since it is Wano. It will probably have to do with Zoro since he now carries his sword. Up top is just how I can see it happening.
*Theory by ChosenYasuo