I would think it's obvious that the point of having Yamato and Momo both being the inheritors of Oden's will is that Momo is the one who will stay in Wano to be the shogun like Oden, while Yamato will take on his adventuring spirit. Momo is already going to stay since his dream is to be shogun. If both stay (or leave, but I don't see Momo leaving Wano except for the final war) then Yamato has no point as a character. All she will have contributed is giving Momo Oden's logbook, something that Shinobu or one of the other Scabbards who stayed in the past could have done. Yamato adds nothing by being a +1 to the long list of allies and forces that will exist to protect Wano (the Scabbards, the Yakuza, the Samurai, the Ninja, the Ex-Beast Pirates, the Minks, and now Zunesha itself) on top Momo having Kaido's power himself, and there's another layer if Luffy/Momo declare Wano as Straw Hat territory. Yamato is not going to be the one that makes the World Government go "Oh, we can handle all of those other guys (even though just the Samurai themselves were considered enough to stop the WG from interfering), but this one person is the straw that broke the camels back." It's even more glaring since CP0 haven't commented on her at all. The only time she was kind of suggested was when they mentioned the Straw Hats causing problems and leading the charge in the raid and Yamato was included in the panels showing the Straw Hats fighting, but she wasn't brought up by name at all.
It would also be extremely out of character for Oda to have a hero (Momo) stand in the way of someone's dream by asking them to give up something they wanted for decades just so they could stick around because he wants them to. Even more so since the Scabbards already fill the role of being his guides in becoming a shogun and as defenders of Wano and both Yamato and Luffy have been pushing Momo into taking responsibility for handling things on his own without having to rely on them. It's just bad writing to waste panel time by undoing all of the characterization, dreams, and the relationships with those who held her back and those who pushed her forward, just to accomplish none of that because Momo needs another babysitter.
*There were quite a few posts in between this and the discussion on Momo/Yamato staying, so apologies if this seems apropos of nothing.