I think people are underestimating Mario Maker, it's easily the most marketable of the bunch, I can already see the TV commercial with sprite Mario and then a human hand changing the environment around him "Finally, you can make and share your own Mario levels, only in Mario Maker", that's a concept anyone can understand.

I think Mario Maker will actually be the Wii U's best selling game in Japan and Europe next year, yes even above Zelda (and before you scoff, go actually look at Skyward Sword's sales in Japan/Europe).

Plus I think they could very well add Amiibo support to it (get sprite Kid Icarus, Samus, Link, etc. into the game?) and maybe they can cash in on some of that Minecraft hype of custom world building.

Splatoon I think will sell in line with Pikmin 3 and Yoshi will sell in line with DKC: TF. I actually wouldn't be terribly surprised if Mario Maker outsells both combined. If Nintendo is smart they will launch Splatoon alongside an animated TV series and amiibo toys/general merchandise to get its name out there more. 

No one of them. Even DK:TF can't boost sales. Wait for Zelda U.

Splatoon, but I think Xenoblade should have been 1st half as well.

Splatoon.
I have high hopes for the title!

Ummm, yoshi maybe. Its pretty weak to be honest.

I cant see myself purchasing any of these, so the first Wii U game I'd be getting in 2015 would X or Zelda

Nothing else is coming in first half? M sure Nintendo can arrange some third party titles. If they can convince WB to make Wii U versions of Arkham Knight or MK X it would help way more than these titles

All of them!!

As a MASSIVE Nintendo fan here, this is what 2015 has in store for the Wii U.

Xenoblade Chronicles X will be released, Zelda will not (we will get overloaded with information on it though), Star Fox might but will not impress because it will be a rushed effort to bring a Wii game to the Wii U (making many wonder why they didn't just scrap the Wii project and start on a new Star Fox from the ground up that takes advantage of the power of the Wii U), and the big show off at this E3 will be Metroid (2016). The small show off is around Oct of next year (2015) we will get Fatal Frame 5, but will still not get Fatal Frame 4.

For Nintendo fans who have been with me since the Wii U dropping, they will know from experience this is exactly what is going to happen. Not to say that these games won't be amazing and I will pick them all up and greatly enjoy them, but pushing major titles back is getting tiresome.

I agree with everyone who is saying none of these are system sellers. It honestly could be any of these that boosts the console most, but whichever does it probably won't be by that much.

I say Mario Maker since I think it'll have an inevitable bundle.

Mario Maker will outsell Xenoblade, Splatoon, Yoshi fairly easily at that IMO.

Zelda is the only game next year that WW may top Mario Maker and even there I think Mario Maker sells more in Japan and Europe.