I doubt Microsoft will allow Valve to put it on for free, or at all
The map will either come out in a pack with the other two maps, cp_goldrush and cp_badlands, or simply, will not be released at all. The 360 version really is missing alot of new updates. For example, the exploit in dustbowl (shooting through the starting gates) which was taken out of the PC version is still there, also things like the new stairs on dustbowl etc are not there.