I'd estimate that Sony will maintain it's lead until at least next holiday season. M$ will drop the price to $399 once Halo 5 arrives and should be able to pull ahead by end of December 2014.
If M$ does release a Kinectless Xbone after the Holidays at $399, I'd assume they will surpass PS4 sales in N.A by Spring.
" Rebellion Against Tyrants Is Obedience To God"







