There was a theory goes around... that one of the crew will leave after wano, and its zoro, after learning his backstory in wano zoro will finally realize that he can become stronger without the crew, and luffy will not be able to convince zoro to stay.... in the end, zoro will see luffy as the final opponent to become the strongest, thus theyll fight to death, ....
This theory were made by a fan who obsess wants a good rivalry story, which one piece lacked, and oda already realized this and follow kishimotos way....