I'm still predicting Q4 2013 for next Xbox and I'm sticking with that for the moment. The Wii U doesn't sound like it's going to be that big a jump to worry 360 in US and I'm not convinced Nintendo will have the online sorted out to make it compelling vs Live.
In short looking at sales this year I expect 360 to have a strong 2012 too, then MS to allow it to wind down a bit in 2013 and shift to the new console - while still supporting 360 for another year or two at least assuming sales hold up in US for the 360 with another Xbox on the market.
Try to be reasonable... its easier than you think...







