There's actually a great chance that the man talking to Crocus is actually Shimotsuki Kozaburo.
- We never have seen him in the manga
- We don't know his and Crocus' relationship but they could have just met each other and became friends
- He is wearing a Wano hat and kimono specifically.
- We know now that Roger didn't pick up any other Wano crew members outside of Oden.
He could be returning to Wano to die or because of the 20 year prophecy. He could also in fact be the one to tell Zoro about his lineage if the fighting shifts onto mainland Wano and they meet.
Remember, this is the "old man" Zoro is referring to that used to say "Sunacchi". He also forged 2 of Zoro's current blades. That's a big deal. It would also mean Oda has been planning this for almost 10 years now