Football is always evolving, always progressing. Everyone is looking for an edge to help them.
I read an interesting article about the spread offense with a QB who can throw well and run well (like Manziel, but there are others). The author's point was this: these dual weapon QBs have moved the audible forward in time, to include during the play.
The old audible was come to the line, QB reads the defense, and changes the play as necessary, snap the ball, go.
With the mobile QB and blocking (important skill here) WRs, it is come to the line, change the play if necessary, snap the ball, drop back, read the defense again, and change the play again (from a pass to a run), with the WRs and linemen adjusting responsibilities on the fly.
A real-time audible if you will, during the play.