I wonder if they are planning to release a lot of the missing things, such as boats, cars, other aircraft, radio communications, and so on, as more DLC.
It seems like quite a logical move. Something like 'Looking for some company in the sky? Don't want to deal with Noobs? Lucky for you, we present the 'Crowded Skies' DLC! Now you will see AI versions of every aircraft you currently own as DLC flying around, completely independent of you!'