I was always skeptical of the speculation on this forum by some that XboneX would be partnering with Oculus Rift - and that E3 would see an announcement. The closer we got to this point the more some kept on affirming that an announcement would be made and that MS and Oculus VR (OVR) were still buds.
Well I think we can see that there is no plan for XboneX support of Rift at this point, and to be honest there was never any plans (beyond over aspirational hopes by fans). The MS / Oculus relationship has been shaky at best. As we now seem to realize that while a certain executive tried to claim that the "shortage" at the Rift launch was not as rumored due to Gamepad supply, later leaks now seem to point to this was one of the issues.
Also, the level of "comfort" that MS management has felt dealing with the previous team at OVR has seen minimal if any interaction. A source at MS Redwood R&D confirming that they had not spoken with any OVR executives in months. So, to see all the speculation here that MS and Oculus were still an item... seemed hyperbole based on desperate hopes, rather than any reality.