Windows MIxed reality headsets and 4.18 - SteamVR... are they compatible?

I would have thought that by the time that Microsoft and Valve sort out SteamVR support in December that you can run ANY SteamVR game on those headsets via a translation layer, the same way that Vive games work on the Rift. So in theory you SHOULD be able to run a Vive or Rift project without taking any extra steps.