Regarding new series, Astral Chain and Golden Sun seem like they'd be locks if we get a new title from either. Rhythm Heaven should also fall under this category, but if whatever prevented Chorus Men from getting fully realized persists, maybe they'd run into trouble.
I think Wars will probably get a character if the remake is successful enough to prompt an entirely new title. And then there are other series less likely to return, but if they do, they stand a good chance at representation, just due to their number of titles/previous popularity, like Starfy, Custom Robo, or especially Takamaru.
And then with Ring Fit, I honestly think they have enough in their favor to just be included as is. The game has sold, like, 15 million copies. That's absolutely insane for a new IP. That's higher than every Zelda game but one. But if and when the series continues, that will only be the cherry on top.