When will PS4, X1 triple the Wii U in sales?

[Kerotan]

OttoniBastos said:
Ps4 will probably triple WiiU when it reaches ~30 million consoles(ok maybe a little more :P).WiiU is still struggling to reach 10 million and PS4 will probably be close to 25 by E3.

When do you think ps4 will hit 30 million?