X-Plane 11 and MacOS Catalina
X-Plane 11 is compatible with MacOS Catalina (10.15). While X-Plane works with Catalina, a number of users have reported problems with third party add-ons and Catalina's increased level of software security. If your X-Plane setup is heavily enhanced with add-ons, you may want to remain with Mojave.
The X-Plane 11 Professional-Use USB keys will require updated HASP drivers, available here, to work on MacOS Catalina.