They'll duel for a little while. PS4 will pull ahead when Sony starts shipping enough, depending on what kind of games they have coming for the spring/summer. 3DS will get back in front during the Holidays and when big games release (Smash Bros this year, maybe Pokemon, etc). They might be about even next year. As the 3DS gets older and the PS4 starts to hit its stride, obviously the latter will take the lead. There are a lot of variables though.