If we take what we know about the PS4 and what we know about the next Xbox by the rumors the answer will be no when looking at it with a historical context. The PS4 seems to be the most power of the three with the RAM being the deciding factor between the next Xbox and PS4. And historically in none of the previous generations has the over all "powerful" console had the best selling system. Taking the last three gens the "winners" were the PS, PS2 and Wii. And the most "powerful" consoles for those gens were the N64, Xbox and PS3.
Though depending on what Microsoft intends to do with its machine it may be a two horse race between Sony and Nintendo, that is if Microsoft continues it Live initiative making the gaming portion a portal that can be accessed anywhere, which may be the case since there where indications that Microsoft is looking into building it own streaming services, which would make the next Xbox little more then a media center portal. Then it comes down to who can keep the prices low and get the games.
To be fair though... this situation is a bit different.
The Wii U is currently floundering around gamecube levels i believe. (possibly even lower.)
Which unless there is a PS3 like comeback relativly soon, or the gaming market has shrunken quite a bit, likely means it's going to be out of the picture. It isn't impossible but i wouldn't bank on it.
That leaves Sony vs Micorsoft... and Microsoft has shown issues selling outside the US so far. The two wil be a LOT more close technically then a lot of people want to believe, but even still, i wonder if Microsoft will be able to penetrate Europe enough.... Europe caring more about racing and FIFA then the US cares about FPS and Madden. and Playstation argueably has an even bigger reputation for those games. (Gran Turismo basically being a bigger deal to racing games then Halo is to FPS.)