Well from what I jusr read it appears that Milton Shupe is Retiring pretty much from Full Time Flight Sim Projects , but will be updating his previous Flight Sim Aircraft for use with FSX / Prepar 3D.
Read about the interview with Milton Shupe the great Freeware Aircraft Designer
Sure gonna miss him, his aircraft were a joy to fly !!
Interview Link : https://www.flightsim.com/vbfs/content.php?18089-Milton-Shupe-Developer-Interview