The more I think about these rumours the more it almost makes sense in a way. If MS brings out a new xbox console next november the 360 will be on the eve of it's 7th year of availability. That's a huge amount of time for a console to be available without a successor. Plus, it's not as though the 360 is just going to disappear overnight. They don't have the supply issues they did with the original xbox , so I'd expect to see 360's built right up until 2015 or even 2016. The new console will probably last until 2018.
It just actually seems like the right year to launch. Nintendo WILL be out next year with the new wii, sony is bleeding too much money as it is and launching the vita. They won't be in the picture until 2013 for sure. And I think this time they'll make a point of exceeding the specs of the other guys instead of basically matching them.
Either way, Wii U out in september with a huge launch (say 5 million shipped from sept-dec worldwide) , lots of software and a price of no more than 249.99 USD. Microsoft will have a hard drive using 360 available for 199.99 USD to compete and a 149.99 model with no HDD. In November I see them releasing this new xbox with only 1 limited edition model for 399.99 , 300,000 units day 1 and 100,000 more every week until the end of the year. Launch will be late november , perhaps just prior to black friday ? European launch will happen in february and japan won't see the system until the summer of 2013. Sure , chances are they won't sell super well but , much like the 360, it gets the system and some software out there and allows them to ramp up production faster to cut costs sooner so by the time the winter games season of 2013 rolls around and the PS4 launches , the wii U will have 200+ games (mostly ps3/360 ports) and the new xbox could have 100 games that will all look better than any ps4 launch title.
It's kind of a scenario I see only because MS already did it once so why would they delay a new xbox into 2013 and thus leave 8 years for the 360 and probably then 5 years or 6 years at best for the new console. It'll be harder to convince people to upgrade to a new system when a new playstation comes out within 30 days of the new xbox, not to mention giving the wii U free range on hardware superiority for a full year. It wont' be leagues better than a 360 or ps3 but I think it'll be a noticeable improvement and for those starved for a new home console, even with similar games many will jump. Especially those that bought a wii and enjoyed it. Some of these people already bought kinect or move but not THAT much.