Nintendo revealed in the Super Mario Maker 2 Nintendo Direct that Super Mario Maker 2 would have a story mode featuring known characters, new characters to the world of Mario and also 100+ courses.
Whilst the original game had Nintendo created courses, there wasn’t a lot to tie it all together, so this seems like a great way to do so with cutscenes and all.
The story will have you rebuilding Princess Peach’s castle, which definitely fits well into the regular Mario theme.