Just like Joker's video, it could introduce one or two extra modes.
New content approaches! Joker joins the playable roster, and updates in Ver. 3.0 include additional functionality, such as a stage builder, video editing, an...
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Joker didn't have a true presentation video, they could "tease" the next character in the first few minutes then focus on whatever surprise they have left.
That's a theory of course and has no basis, but if they have extra content, they could easily do a ten-fifteen video without any issue.
My prayers go towards a Smash Run 2.0