Between possibilities like Blackbeard going to Wano to get Big Mom and Kaido’s fruits and Straw Hats going back to Wano to have Vegapunk cure the Smile effects, I’d say there will be plenty enough reason to go back to Wano soon enough, just in time for Yamato realize a greater purpose that would help Momo out as shogun by finding the answer as to why Wano’s borders should be open + the full context behind Pluton and Joy Boy in regards to Wano, so I figure Yamato has enough potential to have purpose beyond just being Momo’s babysitter.