Sooo, you think that the wiiU is going to surpass the ps4 in the next few months, despite showing no signs that it's going to do so (See mario kart 8), and you think that 300,000 people are going to return their xbox ones, and no one else will buy one? Interesting....

My prediction: 

xbox one: million - 7.6- 9 million

wiiU - 9-10 million

PS4 - 13-16 million

PS4 - 12.5 million
Wii U - 10 million
XBO - 8.5 million
3DS - 50 million
Vita - 10 million

Yeeeeah It is a pretty overly optimistic prediction for the 3DS, prolly more of a hope than a prediction, hoping this is 3DS's peak year rather than last year

When SSB will come out the WiiU will dominate the market outselling the PS4 2-1, people will want the WiiU so much that they will return there X1 and buy a WiiU.

Worst-case scenario:
PS4 - 16,00,000
Wii U - 9,800,000
XBO - 7,500,000
3DS - 53,000,000
Vita - 10,500,000

Best-case scenario:
PS4 - 17,500,000
Wii U - 11,000,000
XBO - 8,800,000
3DS - 57,000,000
Vita - 11,000,000

I'm gonna go on a limb here and say you're a troll. But in the case that you aren't, you have no support to what you're saying.

Mario kart has had 8 insallments, 3 of those intallments can be easily compared to the three SSB games. One mario kart sold nearly double it's SSB counterpart. One SSB sold slightly more than it's mario kart counterpart. Then Mario kart wii sold nearly triple SSB brawl. So, if we look at history (which people seem to forget exists), Mario kart will likely end up selling more units, or near the same. Then we need to add in the fact the SSBU is also being launched on the 3ds, which will end up affecting the sales of the console version as well. Mario Kart 8 was only on the wiiU. So if you look at the facts, super smash bros is probably going to sell fewer systems than Mario Kart 8. I think that the thought that SSB is going to be a bigger system seller is just wishful thinking because mario kart 8 didn't turn around the system like so many people thought it would. The fact of the matter is that the wiiU still hasn't beat the ps4 one week since the ps4's launch. Even the week of MK8's launch. Now I think that this won't be the case with SSB  because I don't think the ps4 has anything coming out that week, but it still says something. I don't think any single game will turn the wiiU around so much that it will end up selling 5-6 million more than what most people are projecting. 

lol you guys are so easy, I can't believe you took me seriously. I think SSB will help boost the WiiU sales as it will bring yet another must have game to the library making it more appealing. I think it will sell probably close to the X1 probably a little more but I doubt it will sell more than the PS4. But who knows.

Lifetime

PS4 - 15 million
X1 - 8.2 million
WiiU - 8.5 million