It is significantly less than Galaxy for Japan, but still not terrible, especially given Wii U's smaller userbase

No, the sales are dissapointing. This is the direct sequel to SM3DLand. When it launched in Japan it boosted 3DS sales by more than 100% that week. It went from 60k the week before to sell 130 the week Mario 3D Land released. The install base at that time for 3DS was 2,2 mill. 

This is why some people believed it would do much better than it did. Especially since its been much better recieved by the media in comparison to its direct predecessor. 

At the same time, i'm pretty sure it will do far, far better in the Americas. I dont have high hopes for Europe, but i'm sure it will do much better there than Japan. Atleast for Japan i'm hoping for a better baseline than before its release.

It will have decent legs in all territories. 

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. 

I will say this: There is no doubt Nintendo wanted a release of both Taiko U and SM3DW on the same day to give WiiU a momentum boost in order to increase the baseline. 

There is still Monster Hunter Frontier G and Dragon Quest X version 2 yet to be released, but none are platfom exclusives so i dont expect them to do much. 

Mario Kart 8 is now the only title i expect will give the U a decent boost in Japan but it is, as you say, going to be a looooong wait. Japan has voted for 3DS and its not looking to change anytime soon.

"How bad will selll Mario 3D World"

You mean,

"How well will Super Mario 3D World sell?"

will go on to sell 8m+ WW LT =D

Wow, this guy is an asshole. 

yeah, imma report him

It's all about the legs!

Why would you report him?  He's just correcting poor grammar.