I think when it comes down to it Moore is better right now than Showers and Dak, obviously, and the coaches trust him more if Romo goes down. But Showers and Dak's upside and potential is far better than Moore's. They'll keep 3 QBs, final cut will be between Showers and Moore. Showers has to show he's ready and can step in when needed.
For the preseason I say give Romo a few snaps the 1st game and give him a full quarter the final game. Let Moore and Showers start the 2nd and 3rd games and each run with the first teams for a half.