Those you think PS4 will sell like Wii U are wrong, totally.
PS4 will sell much better than PS3 and better than Wii U.
It will be more like PS2 was in Japan ( 15-20M only in Japan) , it will show you Japan home console gaming is not dead. Quote me on that. ;)
I remember when Wii U failed here, everyone was saying that microsoft/sony consoles wouldnt do better, then, they did...
Predictions for end of 2014 HW sales:
PS4: 17m XB1: 10m WiiU: 10m Vita: 10m