Low sales means that this series will be put on even lower priority

Though I do wonder how much Metroid Prime would have sold on the Wii U if it was what the fans wanted

Easily 1-1.5 million. The Wii U doing bad, shouldn't of done anything. Prime survived the Gamecube hate. Unless they forced garbage Gamepad functions like Star Fox. Like putting the FPS camera on the pad. And had a side scroller view, on your TV.

I'm not sure..Donkey Kong Country Tropical Freeze sold about a million units on Wii U, when its predecessor sold about 5 million on the Wii. Pikmin 3 sold about 1 million along with Yoshi's Woolly World. Wind Waker HD sold about 1.8-2 million. I think a new Metroid Prime on Wii U might have barely made it to a million, especially if it was not sold during the launch window of the Wii U. I guess with better advertising, Metroid could've sold around the range you pointed out, but if we go by what Nintendo has done recently in terms of advertising their games (with the exception of Mario Kart 8, Smash 4, Super Mario Maker, and Splatoon), brand name alone wouldn't have been enough I believe.

Exactly. My two friends had played it so much and talked about how much fun they were having so i finally ordered a copy.

You're comparing sales on a console that sold 100 million to a console that's only sold like 13. If dkc sold 5 million on the Wii it had an attachment rate of about 5%. Compare the Wii u numbers and tropical freeze did around 7.5%. The Wii u typically has better attach rates than the Wii and metroid could have seen success based off of that. 

The game failed me because of the control scheme. I wanted Metroid Prime: Hunters 3DS. It did not deliver.