Its hard to say really, but I would say wiiU.
I believe that there will be around 80M ppl that will buy a PS4 as their primary/only console worldwide. These people may have a gaming PC too. I also believe that in addition to that around 20-40M people will buy a PS4 and at least one other console.
The WiiU/XB1 each have the potential to sell at least 20M exclusively as a primary console. The real question is, those 20-40M people that will buy a second console in addition to the PS4; which platform will it be. Nintendo or MS? I think that is what determines who becomes second.
Already having a PS4, I personally feel if I were ever going to buy a second console this gen, its definitely going to be a wiiU. But thats just speaking for myself.







