These are my ideas for how SMW2: Yoshi's Island could work as a style in Super Mario Maker 2. At first it may seem vastly different to the other game styles, but so does Super Mario 3D World. If I had to realistically guess what other style Nintendo could include in SMM 2, this would be it. Currently there are 2 backdrops, but I plan to make more soon (if I have time).
Sprites taken from The Spriters Resource.