Neither Kid nor the rest of the Supernovas are real rivals to Luffy. They could have been but it's been obvious since Dressrosa, where Luffy bear Doflamingo and showed that he was far above Law and got his own allied fleet, that the manga wasn't going in that direction, and I don't think that Oda ever really wanted it as it was due to his editors that he created the Supernovas, with Wano where Kid joined the Luffy cheerleaders wagon, and its aftermath being the final nails in the coffin.
Kid will surely return but he will never be Luffy'd rival or equal, and will surely become one of Luffy's ally again.
And I am skeptical about Luffy fighting Shanks, since he didn't really have any fight with Big Mom, and even if she returns in Elbaf I doubt that she'll be an antagonist again (not for long even if she does) with her turning into O-Lin for good this time, while Shanks is fated to have his great confrontation with Blackbeard.
Kid will surely return but he will never be Luffy'd rival or equal, and will surely become one of Luffy's ally again.
And I am skeptical about Luffy fighting Shanks, since he didn't really have any fight with Big Mom, and even if she returns in Elbaf I doubt that she'll be an antagonist again (not for long even if she does) with her turning into O-Lin for good this time, while Shanks is fated to have his great confrontation with Blackbeard.
Rest might have same goal but they don't get the same rivalry portrayal like Luffy and BB