Previous reports pointed that Microsoft is working on two version of Xbox vNext from which one will focus on high-end gaming and other about low-cost media console. The low cost Xbox vNext dubbed Xbox Mini/Lite will have Apple TV like functionality and will not have any harddrive. if you want to play Xbox 360 games, you have to buy and play it on demand similar to services like Gaikai. VGLeaks provided a brief description about Xbox Mini, read it below.
The “Xbox Mini” is not a 360 add-on, it is a stand alone product that contains Xbox 360 functions for gaming, and alone it is meant to compete with Apple TV. Since it is likely it will not have a disc drive, it is being designed with “always online” in mind, and with internet being required for Live functions. Xbox 360 Games can be played on it by purchasing Games on Demand on Xbox Live (for new purchases) or if already purchased, simply download it. This also applies to music and movies. To further clarify, the Durango will also have these (TV) functions, just with next-genration gaming hardware instead of Xbox 360 at a higher price.
When used with Durango, it offers connectivity with it for backwards compatibility with both disc based and On Demand games, and it’s no more different than what Sony will be doing with Gaikai for playing PS3 games on PS4, only with Xbox it will be done locally and not through the cloud. You can control the Xbox Mini under a single interface and not have to worry about switching between devices in a single display input. These connectivity functions cannot work with existing Xbox 360 units due to the difference in external interface. The Xbox Mini was designed for this along side Durango.
Read more about it from the link below.