MS is no stranger to coprocessor design and looking at the custom chip they created for HoloLens coupled with an Intel Atom Chipset, I could easily see them performing the same thing with the next gen system. With multiple engine studios saying they will support DX12 Ray tracing, now would be a perfect time to invest in a custom chipset to showcase the tech and maybe bring it into the now.
https://www.theregister.co.uk/2016/08/22/microsoft_hololens_hpu/