My prediction for Darth Vader in Rogue 1 is that Vader will be ... VADER! By acting as he does in all the other movies, Vader will be doom threatening Krennic. And because we already know that Vader keeps his lethal promises, we know that Krennic will feel "motivated" to stop the Rebels at all cost. And his desperation will grow larger as he bargains for more time.
1. Killed by Vader. 2. Killed by Vader. 3. Killed by Vader. 4. Killed by Vader. 5. Killed by Jyn.