2014.
For it to sale more it would need to take consumers away from the others. Especially the PS4 and that's just not gonna happen. Also U is close to exhausting the supply of ninty fans to sale to.
Another reason is it will be facing an onslaught from PS4 and its games, PS4 with all the 3rd parties and exclusives and indies will be a far greater sales beast then its been already. In no realistic scenario is what wiiu has enough to compete with that. Add potential morpheus and PSNOw to PS4s aresenal.
U had a good chance to build up a relevant lead that would get it support and chance to up sales later. But its a bit late for that. So 2014 will be its potential highest year. Unless it can be some how marketed as a awesome secondary console to the PS4. A Wii60 type deal.







