If the SDK includes information on DRM and the XBox Live protocols, one might be able to devise a compatibility layer on top of a standard x86 compute platform to run (not emulate) XBox One games. But, given the hardware specs, I'm not sure if this would be more economical than just buying an XBox One. You would also presumably require a ripped XBox One BIOS.
8 core AMD Opteron (XBox is custom AMD 8core) = ~$50
ACS Mobo = ~$30
8 GB DDR3 = ~80
8GB Flash Rom = $0 (Emulate via HDD?)
Blu Ray Drive = ~$60
500GB HDD = ~$45
AMD HD 7850 GPU = ~100
--TOTAL: $365 (Not including Controller, PSU or HTPC Case)
--Xbox One with game and controller: $350
But if you already have the hardware, then cross your finders and wait.