Sales by 2020:
Wii U = 39 Million / NNC = 16 Million
PS4 = 91 Million
Xbox One = 53 Million
PSVita(with VitaTV) = 48 Million
3DS = 141 Million
Note: NNC - New Nintendo Console Launching at the end of 2015, while i personally don't believe it will happen at all (Its existence or not won't change Wii U numbers).