I propose these games for the Switch 2.
>Princess Peach Showtime 2 with a different villain or even the official debut of Wapeach
>Bowser solo game with a new villain for Bowser himself to fight (BiShitters need not respond)
>New Wario Land with Captain Syrup as a second player with her own campaign
>Waluigi solo game with its own atmosphere, style and cast. Genre unknown
>Yoshi game that isn't a retread of Yoshi's Island with a different arts & crafts style
They have an all-star cast that can hold their own in a solo title and they aren't using them like they did in the 90's. This is the real issue with Mario, never mind the stagnant NSMB era or Wonder being lackluster and piss easy, they used different characters for experimental titles and it often worked. You won't get a Wario Land or even a DKC nowadays, Bananza only exists because of DKC, not the other way around. Better hope someone really loves Wario Land in Nintendo EAD or EPD.
I don't consider Mini-Mario as its own protagonist, but otherwise this chart showcases what I want for future titles.