Zoro will have to train the next generation because nobody in the current gen will be able to be his Shanks. Like, even if Luffy does survive, leaving the crew, if it has not already disbanded at some point prior to him making this decision, would be what Zoro would do. I do not see him sailing with Luffy in perpetuity even if it is an option.
Their current lifestyle of going on big adventures if good for him now since there are still foes to overcome but at the end of the series after he beats Mihawk? It would become boring real quick to fight the silver medalists of the world and the fodder below even that. And unlike Mihawk I do not see Zoro just sailing the seas stomping fodder pirates as a hobby.
Be it Wano or going back to his old dojo he is gonna start his own school to maybe create a worthy apprentice that can take the title from him one of these days. He is only twenty-one now so if another Zoro is born right now in the manga, by the time he is as old as Zoro now and can challenge him Zoro would only be 42, still a year younger than Mihawk is now.
I personally put a lot of money on this exact scenario going down btw. Either an honest to god Shippuden-esque sequel or a brief Epilogue will show Zoro effectively being a healthier version of Mihawk that trains the next generation to surpass him instead of suffering from the boredom of being the strongest swordsman. With people like Momo and S-Hawk as potential students depending on how things go, he has a good enough baseline to work with to keep himself occupied after the end of his pirate days.