Titanfall will significantly boost Xbox and I would expect a price cut soon to keep the momentum.
But Xbox selling better won't stop PS4 from selling. So PS4 should get to 15m first easily.
Wii U I expect to be last to 15m.
Bet Shiken that COD would outsell Battlefield in 2018. http://gamrconnect.vgchartz.com/post.php?id=8749702