If it's crap ... We'll tell you
Civil War would be an AWFUL film, because it requires to much story.
Red Son, while a good Superman series, would only work as a direct-to-DVD POS like All-Star or Red Hood.
While I know quite a few comic fans that would like to see this happen, I think this is one of those properties that would show a clear divide between "us" (geeks) and "them" (the masses). I think the sheer amount of mass murder that is committed wouldn't fly for a marketable super hero movie. It deals with some great issues, but for us, not them. The "What If Superman flipped out" conversation is a great geek debate, but I don't think normal people care, and would probably be disturbed rather than enertained by a film version.