Can I be honest?
While I would appreciate to see them working on something more "mature" (yeah, I'm just talking about the style here
), I would be very, VERY interested to see them on a platform-adventure more in the veins of Super Mario 64 / Jak & Daxter / Banjo & Kazooie / etc. Especially because...imagine if they obtain to translate the background and frontground intense scenery action fron their DKC games (just background, background-to-frontground, frontground-to-background, just frontground, both separately, etc.) in a 3D space for a more "old school" platform-adventure game.
...I don't even know if it's possible, but I would like to see their take on this genre too