And it's out right now.
http://www.nintendoworldreport.com/news/72418/donkey-kong-bananza-gets-first-dlc
The adventures of Kong have been expanded, for those who wish to partake.
Nintendo revealed the first (only?) DLC for Donkey Kong Bananza today, a two part DLC called "DK Island + Emerald Rush". It is now available on the eShop for $20 US or equivalent.
The two parts of the DLC include an option to bring Pauline to DK Island and hang out with the inhabitants, and the postgame "Emerald Rush" mode which involves finding as many emeralds in the environment under a time limit while gathering powerups and new abilities.