Ps4

Nop, you forget too much things in your analysis, PS4 has more system seller and can push much more than 20k, you forget games like MGS V, Yakuza or FF Type 0,  Dragon Quest Heroes ( for sure it will push much more than 100k alone ( depending on how many collector they have )) and all the other games. PS4 will have at least 20 average system seller to push it to 15-20k, while Wii U has 3 or 4 at the best.

And FFXV could release in 2015 too, which would be a total win for PS4 during christmas

I want to say the PS4 will outsell the Wii U in 2015, but it wouldn't completely surprise if somehow the Wii U was just able to beat the PS4.

I can't see PS4 coming close to losing to the Wii U. It will have a much steadier stream of games in 2015 than it did in 2014 and also more Japanese orientated games in 2015 than 2014. While I don't think it will set Japan alight, I do think PS4 will sell comfy enough to breeze past Wii U.

Probably PS4. Nintendo really doesn't have any huge IP for Japan in 2015.

Zelda is not a big deal there, not anymore. Skyward Sword only sold 400k and it had a bigger userbase with the Wii. I think Mario Maker will actually outsell Zelda. 

PS4 will have things like Metal Gear Solid V and Dragon Quest Heroes and maybe Final Fantasy XV. Uncharted IV will probably do OK there too.

Neither will have great sales though. I think you're looking at a baseline of 10-12k for the PS4 versus 6-8k/week for the Wii U with the PS4 getting a few extra bumps due to key game releases. 

Vita will outsell both. 

Honestly, i think that even Metal Gear P.P will coming in 2016...With this PS4 will probabily sell 25,000-30,000, but not next year.

If Final Fantasy XV, and Metal Gear Solid V will resaled next year, PS4 will outsell Wii U, but i don't think, so, PS4 will outsell Wii U the first time in 2016, IMHO.

Given that I don't see FFXV or MGSPP coming out, reliably, in 2015, I would say its hard to judge. I think the safe bet is to say, at the moment, that the PS4 LTD (in Japan) will not reach WiiU LTD in 2015. If the two aforementioned titles do not come out until 2016, I think that's a guarantee. As to whether or not the year will be won by the WiiU or the PS4, that depends on how the titles stack up and how the momentum carries over from title to title.

A lot of the PS4 titles feel like they're not going to contribute to establishing a higher baseline, WiiU has similarly inconsequential titles but less numerous as they just have less games in general. Both consoles will likely ride out 2015 with miserable numbers, and whoever wins is a bit of a toss up at the moment.

Nah, I'm willing to bet that we'll see a PS4 baseline next year that is equal to, or greater than, the PS3+PS4 baselines this year.

Where are those PS3 users going to upgrade to?

Ps4 will sell more, sure, but everyone here forget that even Wii U will get some games besides Smash and Xenoblade, games that we don't know yet.

The PS4, it has a whole onslaught of games coming out in 2015 that will give it decent boosts throughout the year. The Wii U has some awesome games coming out for it as well, just not enough to keep it on top imo.