There is a great Q&A at AvSim (http://www.avsim.com/topic/483642-ask-d ... simulator/) but some things aren't clear. I think Exploremore is right that VR is kind of niche for now so with building a new engine and all, they probably should put resources where they get the most benefit. They have indicated VR interest so as long as they keep an eye on that pipeline we should be good.
People have asked about 3rd party development and Dovetail said they would be working with 3rd parties. Someone asked if the add ons would have to be sold through Steam or devs could sell through their own websites or other flight sim aggregation sites, but no good answer that I could see. At least it looks like 3rd party devs are being embraced. Hopefully things will be such that 3rd parties can do well however it works out.
I think if they do it right, we can have a civilian flight sim that looks as good as DCS or Assetto Corsa and fixes or extends all the things about FSX that have been needing attention since Microsoft abandoned it. VR is just getting so cool.