It is, of course, much too early to say Sony will win the gen. Right now their approach seems solid, with a reasonable price, a good system and strong 3rd party support. At the very least they should do well, especially when you look at the solid sales of the PS3.
XBox should not be disregarded. The XBox brand is the "it" brand for video games in the US right now. The $500 price tag will kill sales for the One at launch with an equally good alternative available for $100 less. However, MS could change the price at any time and even the playing field if they so choose. Since neither system has even launched yet MS could even change price before launch so it's silly to say what the lifetime sales will be at this stage.
Wii U is currently selling poorly, but I wouldn't count it out either. It presents the cheapest option and the most unique hardware, as well as the most established exclusive software. Nintendo has also shown a great history of developing the "next big thing". The DS was thought to be lost cause against PSP until titles like Brain Age and Nintendogs came along. Wii Sports totally changed things for the whole industry, and so did Wii Fit. While those trends may or may not be dying or dead, it would hardly be surprising if Nintendo released the next hot seller sometime soon that made Wii U and its dual-screen action a must-have item.
So sure, PS4 looks in good shape right now. But things could change with an XBOne price drop. They could definitely change if Nintendo dropped the price and released something innovative on Wii U in the near future. This is especially true for Japan, since PS4 seems to be getting off to a very weak/late start there. I can see several scenarios playing out where PS4 does not lead the industry. Though I can see few where it bombs, either.