What does it even matter what logo Pauline would have? I doubt her existence would preclude a different Mario or DK character from getting in from logo alone anyway. I mean, we just saw two Mario newcomers happen in Smash 4's base release.
Especially since she doesn't really have much to work with moveset-wise, and Super Mario Odyssey didn't do much to aid that. Rosalina's moveset was doable because it used things that were established in Super Mario Galaxy--being basically a godlike figure with cosmic powers who watches over the Lumas. In contrast, we have nothing that'd link Pauline to Cappy other than them both showing up in the same game. They don't even interact with each other, much less ever work together!
I do think she'll start showing up in Mario Kart and other Mario spinoffs now, though.