I would not call development stopped. We still get bug fixes and just had a few new planes.
Development is current centered around their next game which is being planned and developed as we speak.
Cargo and FBO have been heavily requested and while I would not hold my breath for an official release soon™ we may one day in the future get them. I’m only giving a fraction % chance through from the Devs. 
I would however suggest taking a look at this Mod/Thread.
You might even share your ideas with the Dev, Cargo is sorta implemented already.