We just got this from DTG:

Earlier this year, we announced the development of our new flight simulator, which generated an incredible amount of excitement in the community. We would like to thank you all for the tremendous amount of interest and support we have received so far.

Based on your feedback, we have been focusing on three key areas: visuals, performance and experience, all of which are instrumental to the hobby. In order to further enhance these areas, we have made the decision to postpone the release of this project.

In the meantime, we expect to have a detailed development update for you in the New Year. As a team, we are incredibly excited to share what we have been up to! Until then, we hope you have a fantastic holiday season and look forward to making 2017 a great year for flight simulation.

-Dovetail Games Flight Team

We would all love to see things going as planned but, sometimes (and, in software development, most of the time) it doesn't.

Let's hope DTG is managing to get the product up to the quality they want to (and our community deserves). Go DTG!