What I would LIKE is a really big swing, a big change to the gameworld (something like an open world would qualify) in which you can use a maximal Mario moveset. In other words, start with Mario 64 moveset and further expand on that, rather than weakening that moveset and augmenting it with gimmicky powerups or gameplay elements... which is the vast majority of the 3D mario games have done since Sunshine.
But unfortunately my prediction, as always, is we'll get a game with no major innovation in terms of the gameworld, no real complexities/variation restored in terms of movement, and it'll be a game in which the "newness" and appeal will be focused around a gimmicky (likely lame) powerup -- the cat's bell, putting a hat on a T-rex, stuff like that.
I consider Mario Galaxy fairly gimmicky and not a great Mario game (but a very good game) but even hoping for that feels like a bridge too far. That may not be a world that represents what's best about 3D Mario-style platforming in my eyes, but it IS at least a really interesting world. But considering 3D World & Odyssey, it seems clear they aren't that interested in giving me what I want.
I hope I'm wrong. I'd love nothing more than to see a Mario that looks really intriguing to me. And for me, that would look more like 64 than anything else that has been released in the last 30 years -- simpler (but big) worlds, and a more complex and varied moveset that doesn't lean so heavily on powerups to be "interesting".
