The Xbox One is x86/64, so emulation shouldn't be necessary for the MCC. The remaining questions are how much it is a "port" from what was released on the Xbox One.
- Supposedly the early Xbox One games used a fork/version of DirectX that wasn't ever quite released in that form in Windows 10. Rumors are that has been corrected in the upcoming April Release.
- Also, the early Xbox One games used very different Microsoft Store asset servers/etc. The State of Decay Insider tests seem to indicate that April Release of Windows 10's Microsoft Store can now speak to Xbox asset servers/etc directly. (Indications that the State of Decay game installed from possibly the exact same assets in the April Release as it would on an Xbox One.)
- Finally, early Xbox One games sometimes made assumptions that they ran in lightweight VMs with almost no multitasking (except for Kinect-related restrictions when that was mandatory) and some very specific performance characteristics versus the wild west of available PC hardware. Rumors abound that Hyper-V improvements in Windows 10 solve some of the VM/multitasking issues. Leaving only, perhaps, the need to test on a variety of PC hardware configurations.
Obviously, a lot of speculation there. Presumably a lot more information will surface as the April Release happens and as E3 approaches.