You know what I think maybe he could make the post credits after all, before I was thinking about how Wario's been less relevant recently compared to how gigantic the Mario franchise is, so I thought maybe they'd sprinkle in a little bit of Wario and Waluigi mayhem for comic relief but nothing too major and that'd be about it. If that happened I'd still be content with it since they make a good duo and lots of their shenanigans in the sports games are funny anyways
But then I thought, if they didn't use Wario/Waluigi, then it'd be in favor of who? Mario, Luigi, Peach, Bowser, Toad, DK, Yoshi, Birdo, Bowser Jr., Rosalina are all in. Daisy? Toadette? Paper Mario for no reason? So I think the odds are looking pretty good for Wario/Waluigi/Maybe even Syrup in a potential 3rd film
With the trailer references I was thinking they'd focus on referencing Galaxy and Yoshi games, but they ended up referencing SMB2 and Odyssey, but I completely understand why, Birdo pairs with Yoshi so it makes sense to throw in a few references to the game they debutted in, and the dinosaur from Odyssey was a pretty memorable thing so Yoshi meeting a real dino is a good oppurtunity to put it in (Also I never played Yoshi's Safari but I know they were thinking about it when I saw what looked like a variant of a super scope)