The odds of us ever getting a true Super Mario bros. 2 sequel seem to get lower and lower each year. And that's probably for good reason. Doki Doki Panic has lent plenty of its assets/movesets to the Mario universe and the games are richer for it, but there's no denying that it wasn't a true Mario game. This gives us the perfect opportunity to revisit that world without the commitment of an entire game, or the very real threat that attempting a sequel could upend the tea set, as it were, of the Mario universe once again.
I think the assets are ready to go and their exclusion from the video was intentional to A) get us clamoring on about the possibilities, and B) give Nintendo a real whammy to unleash during E3, and just weeks before the game releases.
And who knows, maybe releasing these toolsets upon the Mario fandom will give the developers at Nintendo excellent fodder if they do decide to return to Subcon