I hope this game sells very well, because I would love for the DK-styled Mario platformer to return! I know some think that the Super Mario platformers already filled the "Mario platformer" quota (basically a similar justification for saying Mario & Luigi already filled the RPG quota so Paper Mario should do something else), but I personally like and sometimes prefer Mario's original gameplay from the arcade Donkey Kong. As a bonus, it doesn't feature Bowser as the villain this time! Even Donkey Kong as a villain is a breath of fresh air because Bowser is so frequently used.
Besides co-op like they've shown, I have a feeling that a level editor might be added for this game since pre-release versions of this game had a level editor, but I am unsure about it going the extra mile in the same way the Link's Awakening remake did.