That million Nintendo CoD fanbase didn't get nurtured on the Wii, when CoD exploded Wii's MW was a two year old port.
The percentage is nothing new. Let's check the percentage of the last two Wii games, Black Ops and MW3.

BO: X360 (13.83m - 51.13%), PS3 (11.95m - 44.18%), Wii (1.27m - 4.70%)

MW3: X360 (14.03m - 51.45%), PS3 (12.57m - 46.09%), Wii (0.67m - 2.46%)

Nintendo's Third Parties

Given the sales, i dont think Wii U owners care. There are much better games to get on Wii U than the yearly rehash of call of doodie.

This will become a real important question in the 8th gen, especially with the Wii U opting for a CPU architecture that everyone else in the world have practically abandoned, forcing developers to essentially rewrite most of the core code to fit and function.

OT: Well, less sales for Call of Duty is always good news!

I cant wait to see the state of Wii U 3rd party support one the PS3 and 360 become irrelevant

Not gonna change much honestly, almost no PS360 game from this year came or next year is coming to the U. I'd like to see how it'll look like by the time BF5, Destiny 2, Titanfall 2 etc come out though. When those games fully utilize the 5-6GB ram of the consoles.

People are happy that COD didn't sell on WiiU.
But that's a bad sign to 3rd parties. If COD doesn't sell much what will sell?
Just Nintendo games? If it is like that it is worth it to make a port of any game on their console?
COD is called "rehashed" but there are not better shooters on that particular console.

Sales really were bad for this game, but with many opting to buy it on XB1 or PS4 and the amount of stores not even ordering the game (amongst others for Wii U), it`s of no surprise this version isn´t selling.

I say good! CoD should not be expanding, instead it should be shrinking so we can finally move out of the FPS craze and jump into a glorious RPG phase.

Activision is probably not giving as much support because of the poor sales. Activision wasnt very happy about the sales on a Nintendo console. 

So, if EA had made Battlefield 4 (a much superior game by the way) for the WiiU, they could sell 1% more. Good job losing money EA =/