Xbox Live Vice President Marc Whitten elaborated on the situation, saying, "The system is based on a different core architecture, so back-compat doesn't really work from that perspective." This is a similar situation to what the PS4 is running into, where it is unable to play PS3 games due to the switch to an x86 CPU rather than relying on the last generation's PowerPC architecture.
Whitten also confirmed that, as of now, Microsoft has no plans to make this content available via streaming or download. "Microsoft does, however, plan to keep selling the Xbox 360 alongside the new console for the foreseeable future," Whitten said. "This isn't about getting rid of the Xbox 360."
Don't Worry Xbox360 Buddy I Love You Your Not Going Anywhere!!!