The catastrophic part really is that Wii U basically has nothing else for the rest of the year in Japan though. *This* was it, Mario 3D World + Taiko + Wii Sports Club + Wii Fit U + Wii Party U are everything Nintendo was banking on this year.
It's going to be a looooooooooong drought now until Mario Kart 8 next April. DKC: TF is unlikely to fare any better than Mario has (another platformer, doesn't even have the benefit of the holiday rush, etc. etc.). It's less about games now, it's more that people simply aren't accepting the philosophy behind this machine ... it's supposed to a sorta-casual machine and a sorta-core machine, and its just not captivating either audience.
And Nintendo has exhausted Mario in the process.