We will be keeping the coord system the exact same as it is now, using a left-handed system. This is the exact same system that DirectX uses internally, and is the main reason that TV follows suit. Coming from a math background I am used to a right-handed system, myself, but for on-screen display it doesn't take long to adjust.
Direct from MSDN:

DS
Hm I want the Koordinatesystem linke in the Left Picture....
At the Moment it is not...for sure...
As I remind at the the X-Koordinate goes to the opposide Direction and Z and Y are twisted....
The curren Koordinates are all but not lefthanded...
Look at my sample code in the "Why is dies code damn slow post" the Textures are Mirrored so that the engine is painting them correctly because the x_Achis is mirrored in the engine