As mentioned earlier, Microsoft Flight Simulator will be coming out on August 18th. With that announcement, Microsoft also said that VR will be supported and it was mentioned in the press release. Specifically, the HP Reverb G2 headset was talked about, which is natural considering Microsoft was partnering with HP and Valve for this high end headset.
A few sites took that as it was ONLY coming to the G2 initially, but I was skeptical as the press release didn't mention any HMD exclusivity. Yesterday, Microsoft clarified the VR feature a little more as they said all Windows Mixed Reality headsets will be getting the VR feature first with more headsets to come later.
While VR won't be available at launch date, it'll come sometime afterwards and I wouldn't be surprised if someone developed a program to allow for other headsets to play the game in VR while Microsoft has it tied to Windows Mixed Reality headsets. We've seen it for other closed platforms in the HMD space.
With that, those with Windows Mixed Reality headsets will enjoy Microsoft Flight Simulator in VR first. Microsoft Flight Simulator will be out on PC on August 18th on both Steam and Windows Store.