Stick with the Wii U for another year, cause the PS4's library of games is mediocre at best currently.
In a year, if the PS4 really appeals to you, sell your Wii U and buy one. However, if you have enough money at that point and wish to keep your Wii U, it can never hurt to have 2 systems that have vastly different games and (frankly) compliment each other perfectly.
You're Gonna Carry That Weight.
Xbox One - PS4 - Wii U - PC