In a Reddit AMAA, a rumour has suggested that Microsoft's next console release will actually be a cut back Xbox, possibly using an ARM processor and will focus on Arcade titles - designed to be competitive with Apple TV.
Following on from that, MSNerd says there will be a true Xbox 360 successor. The first of the two sounds somewhat like the Xbox Loop that was originally talked about last year, with the latter being much more akin to the rumours that have been circulating about the Xbox 720 Durango.
The Loop like device will likely support the Kinect motion tracker, and that it will be able to utilise the "near-mode" ability found in the latest Windows compatible edition of the hardware.
In terms of timeframe for release, MSNerd is a little less concrete, saying that sometime in "late 2013" is when the Apple TV competitor will hit the market, and that "at some point after that, we'll see an Xbox Next."
Other rumours suggested in the AMAA include the death of the Zune brand and that some of the software will be replaced by Xbox and Windows Phone "Companions."
While some of these claims do back up similar rumours that have circulated in the past, the posts often speak about the ex-Microsoft employee's leaks being a "social experiment." There's also a few swings taken at journalists not recognising when something is fact and when it's a rumour.
So I put rumour in the title. See? All better.