What I would love to see is a GUI for JTAC with a stack of multiple radios and a means to ID when each is being transmitted on. That way a player could act as ATC/AWACS/JTAC for the other players in a mission.
By the way, I like the idea of spetators going to guard, although i would be concerned that if this is implemented, after some time everyone would end up on guard as a common chat and interplane freq, defeating the purpose.