I agree with Gargoyle: Park totally has the martial arts chops but not the acting chops so much (Hi Dave!)
Bradley Cooper looks like Danny Rand but has no martial arts skill. I think this needs more than Keanu/Matrix style kung-fu to really make an impact. This should be a martial arts film that just happens to be steeped in the Marvel lore. And we need atleast a Luke Cage cameo if not a full on supporting part.
I agree that the "Last Iron Fist Story" should definitely be the template for the screenplay. that run was so cinematic anyway, it practically writes itself.