Its at 1.6 ratio right now, but my intuition says it will be less than 1.6 ratio by end of 2011. One main reason is the X360 exclusive title releases (Gears 3, Forza 4, Halo: Anniversary), plus the custom consoles (Gears console, MW3 console, and possibly one more since the Star Wars console will release next year), and lastly the Kinect holiday boost and Kinect titles. Those 3 main factors will keep PS3 from outselling X360 this holiday season IMO.
If MS includes a price cut then the scenario changes and X360 outsells PS3 by wide margins during the holiday months, but it is fair to say that is speculation since there have been no announcements. I personally think some kind of cut will occur however before the major holidays. Even without a price cut from MS my intuition is telling me the PS3 will not stay at 1.6, but will decrease from that number by end of 2011.
