The PS3 sold around 12 million units in 2012 and with the announcement of the PS4 and "XBox 720" I don't think the PS3 will sell nearly as well this year. For consumers to still see a lot of value in the PS3 the PS3 would probably need a significant price cut and/or the PS4 would have to be expensive and lack backwards compatibility; after all, who would spend $300 on a PS3 if the PS4 was $350/$400 and could play PS3 games?
With that said, I'm not sure Sony can afford to cut the price of the PS3 to a level to attract the customers they desire so I anticipate that sales will decline; and I suspect this will translate to sales of 8 to 10 million PS3 systems in 2013. At the same time, I expect Nintendo to sell 8 to 12 million Wii U systems.
This means that I expect the Wii U to perform somewhere between "roughly equal to the PS3" to selling "50% more than the PS3"







