A little different take, not so much in the live-connection vein, but it would be cool to have any building designated as an FBO in the default scenery be able to go in and interact. Sit by the window and watch planes, do flight planning, get weather, purchase fuel, etc. Or simply start there and walk out to the plane (which could be an on-the-rails action or not).
Could also have a pilot guestbook there, of course filtering out or reporting unwanted words/characters. Or it could be automated - date/time, user handle, aircraft, tail number, number of takeoffs and landings. With the ability to not participate, of course.
This could increase the immersion. You could hear the other planes or the rain/thunder/wind while planning (even if it’s just a facsimile of the world map screen). Press a button to hear the audio of the AWOS played, or see the digital readout. Also could provide opportunities for third-party scenery designers to integrate these features into their FBOs. Could be a lot of fun.
And just maybe, the tags of any other participating pilots in the room or on the ramp could be displayed and you have the option to ping them with a friend or temporary flight request, even if it’s just aircraft type and destination.