I wish there was a way to update the game plan during the game. Would it be possible to add this as a type of "halftime adjustment"? I think this would be a realistic addition, as teams frequently change things up at the half in case their existing game plan isn't working. Could also switch their focus to Run if they're way ahead, pass (and fast-tempo) if way behind.

Would this be possible?

The game already has automatic adjustments for run/pass and for tempo based on game situation. But if we wanted to full on adjust the game plan that would be something we'd have to look at in a future version.