One Pece Chapter 1056, "Cross Guild," sets up many things for the story's future. Besides Buggy's new Warlord alliance and Yamato heading off to join the Straw Hats, the Ancient Weapons were also mentioned. Luffy isn't interested in them, but there are plenty of people who would be.
Caribou notably overheard the Straw Hat Pirates discussing the fact that Pluton is in Wano. Once he did, he felt the urgent need to tell a "certain someone" about it. It's hard to say who that someone is, but there are a few likely candidates.
One of the most likely people who would want to know where to find Pluton is Crocodile. Back when he was the central antagonist of the Alabasta Saga, most of what he did was to find their Poneglyph, which would, in turn, lead him to Pluton. It would make plenty of sense for him to still be interested in the Ancient Weapon. If he got his hands on Pluton, it would be a guaranteed way to make him a credible threat again. Previously, he'd been bested by the Straw Hat Pirates, a rookie crew. That same crew has since become much more powerful to contend with the threats of the New World; it's difficult to say whether the same can be said for the former Warlord. If Crocodile were to acquire Pluton, he would be a menace to the New World, the World Government, and possibly even the Straw Hats.
Seeking the other Ancient Weapons might also interest Crocodile. Caribou also mentioned Poseidon, which the Straw Hats also discerned the location of; he might also be looking to share this information. Crocodile's interests may lie with Pluton, but knowing about the other Ancient Weapons would also be a boon.
Learning about Pluton would also give him and, by extension, Cross Guild a good reason to fight the Straw Hats. Since Pluton is in Wano, a country that the Straw Hats recently liberated, they may feel obligated to defend it from beyond its borders. This would be like how Luffy claimed Fishman Island as his territory to protect it from Big Mom; this country also happened to have Poseidon in it. He could similarly declare Wano his territory and defend it from Cross Guild.
Of course, there are still a few more possible people Caribou could be going to tell about Pluton and possibly Poseidon. Blackbeard may want to know about it as part of his goal of world domination, though he seems more interested in doing that with Devil Fruits than Ancient Weapons. Spandam has also shown an interest in Pluton in the past, which could make this an ideal way for CP-0 to figure back into Luffy's story; with that said, him actually getting Pluton might not be the most satisfying outcome, narratively speaking. There could be plenty of people in the World Government who would like to avoid seeing Pluton fall into the wrong hands, only to then become those wrong hands. Likewise, there are probably plenty of pirates who also represent those wrong hands. Alternatively, Caribous could simply be looking to sell the story to a credible news publisher, which could stir up the world in all sorts of ways. It's important to think about who Caribou could tell this secret to and how he would benefit from doing so.
For now, Caribou's "certain someone" statement remains largely ambiguous. Crocodile seems like the most likely candidate, but there are plenty of other people in the One Piece world who could benefit from gaining information about Ancient Weapons. Whoever Caribou decides to relay his information to, Wano's safety will likely once again become Luffy and his friends' responsibility. This is all to say nothing of what would happen if Caribou also ended up being there whenever the Straw Hats happen upon Uranus.