There really doesn't need to be a technological solution to this. Just watching the University of Oregon football team is a perfect example. While their playbook is simplistic to a pro scheme; the purpose is speed. According to ESPN, the Ducks averaged around 20'ish seconds per play. The breakneck (per football standards) pace of play easily exposes poor conditioning. The reason that they play so quickly is that every player looks to the sidelines for the play call. Not just the QB. This ensures that everyone gets the play as quickly as possible without the need to huddle.
I feel that the NFL needs to speed up their plays. A 45 second play clock with no timeouts, as a defense effectively (not always; see Chicago v. Denver) ends the game with anything under two minutes remaining. The NCAA has the same problem.
However, if a technological solution is needed then a broadcast to all offensive players for a play call seems appropriate.