Can't vouch for this cereal leaker but they've been around a while and they seem to post other cereal-related leaks, so take this with a grain of... uh... cereal.
Thanks to Josh Whittington at Mon Amiibo for drawing my attention to this.
And it looks like that might* finally happen. After the kind of digital sleuthing that would put Mario is Missing! to shame, I stumbled upon multiple references, including one with the above box art, to an upcoming Super Mario Cereal from Kellogg's. In true Kelloggian fashion, it pairs oat pieces with colored marshmallow shapes—in this case, crunchy stars are flanked by Super Mushrooms, 1-Up Mushrooms, and ? Boxes. But most importantly, this box of "Mixed Berry" cereal is an Amiibo in and of itself, allegedly able to be used with Super Mario Odyssey for the Nintendo Switch.
Thanks to Josh Whittington at Mon Amiibo for drawing my attention to this.