Apple is expected to release their OS update Catalina (macOS 10.15) this month. This OS introduces new requirements for apps, and also drops support of 32-bit apps, such as Plane Maker 10, entirely.
Catalina and X-Plane 10
If you are using X-Plane 10, we recommend that you do not update to macOS Catalina. The X-Plane 10 installer, Plane Maker, and Airfoil Maker apps will no longer work on this version of the Mac operating system.
Catalina and X-Plane 11
The X-Plane team is still testing macOS Catalina with X-Plane 11, but does not anticipate any major issues at this time.
The X-Plane 11 Professional-Use USB key will require updated HASP drivers, available here, to work on macOS Catalina.