1. The actor will execute the accent flawlessly, like a voice chameleon, making us struggle to remember where Meryl Streep was actually born.
2. The actor will do a terrible job, affecting an accent so horrendous it will distract us the entire time.
3. Like Tom Cruise in Valkyrie, the actor won't even worry about it, while everyone else works on their varyingly good and bad accents.
Now I'm going to make a controversial assessment: Tom Cruise was right. (I just put words together in a way no one ever has before!)
But seriously, in Germany in the 1940s, what is the likelihood that Nazis would be speaking to each other in German-accented English? Zero. They'd be speaking German. With a Salzburg accent. Or a Munich accent. Or whatever.
My point is, if you're going to ignore the language, why worry about the accent? If Americans are playing Germans, let them speak American. OR make everyone speak with accents. (I'm looking at you, Tom.)
But if they decide to go with accents, they can only do the flawless kind. Get a vocal coach if you have to, but make it happen!
This has been trivial concerns with Kimber.