Nintendo's biggest seller ins Mario Kart.

Don't see why not, Wii U should easily sell more in 2015 than what it does for 2014.

4-5 million maybe, but not much more unless it get's a big price cut.

There are two points for discussion here, the capability of a single title to sell a system and having a system reaching a critical mass of must-have exclusives.

For the former point Mario Kart and SSB are unsurpassed, for the latter I think that threshold could be breached, for a lot of potential buyers, next year with the 'smaller' releases.

The WiiU can't win but played correctly it could become a desirable second console. Its standing in this regard is only going to improve with time and weight of releases.

yeah I can see that. people are starting looking at WiiU now really. Wii it's phasing out. 2015 should be better for WiiU.
2016 will be better for XB1.

Xenoblade Chronicles X will give a boost (especially in Japan) and of course The Legend of Zelda. I can't wait for it. Let's also hope that the fewe other "little" titles will help as well.

I'll say 5 million next year.

I think the Wii U will be more atttactive for the general public by 2015 because its library will be bigger and a possible price cut along with the release of Zelda would make the sales explode.

Eh.. Never leave out the next 3D Mario, specially if it's Galaxy 3 or a Mario 64-like Mario game!

I think so too. It's one of those games that makes people stop everything else they're doing and get the game.

Nintendo has done a good job of energizing the Zelda fanbase in the last year or two. Given how quickly things are turning around for the Wii U even without a traditional Zelda entry, I think there's a reasonably good shot at the Legend of Zelda Wii U to actually become the best-selling release of Zelda -- ever...