New Super Mario Bros. 2

[TomGuycott]

Know what I've always wanted to see? Crossovers between regular Mario and Mario RPG content. Imagine you finish the game, beat Bowser and suddenly BOOM!, Smithy's Gang shows up and the game keeps going for a few more worlds. The main reason I'd love to see this is seeing those kinds of enemies in an action-based context rather than a turned-based RPG context.

Bad example though, because I doubt we'll ever see anything from the original Super Mario RPG universe ever again in an official Nintendo title.