Ever since 40/60 year old Sanji came out, I've been thinking about older Zoro, and how he isn't wearing his trademark earrings anymore. There's never been any explicit significance placed on them, but Oda seldom does things without a reason. Could his earrings have represent his journey? He only started wearing them after completing his training at Isshin Dojo, and set off to sea.
Maybe despite wanting to practice Gotoryu, Zoro does start taking it easy a bit by 60 years old, and removing his earrings is a testament of that.
I can see Zoro adopting a Rayleigh-like mentality of entrusting the future to the next generation, knowing his time will soon pass. I think he hands them to someone important, or gifting them to someone he deems worthy to carry them. If he indeed becomes a dojo master like I hope, maybe a student with similar ambitions as he.