Tradecraft: Willem Dafoe Joins A Most Wanted Man

Variety reports that Willem Dafoe is in talks to join the cast of Anton Corbijn's John le Carré adaptation A Most Wanted Man. The trade doesn't, however, mention what character he's in talks to play. Can Dafoe do a Scottish accent to play the lead character of banker Tommy Brue? I would have expected a UK actor in that role, but Dafoe is about the right age. Or will he play one of the Americans who play a relatively small but crucial role at the end of the novel? As I recall, the primary CIA representative was a woman in the book, but that could easily be changed. Since Variety doesn't mention the part, this has caused rumor sites all over the Internet to interpret the story to mean that the actor is replaceing Phillip Seymour Hoffman in the role of German BND spymaster Günther Bachmann, just like they all assumed a few weeks ago that Robin Wright must be replacing Rachel McAdams. (Those rumors were proven false, of course; Wright is playing an entirely different role.) I don't get that logic. Do all these sites (including the trade) simply assume that the picture has only two roles--one male and one female? It's a given that most movies have more parts than that; why does this one prompt such wild speculation? Each time a new star was added to the large ensemble of Tinker Tailor Soldier Spy, everyone didn't immediately assume that meant that Benedict Cumberbatch or Tom Hardy would be replacing Gary Oldman as Smiley! Until I hear otherwise, I'm going to assume that Hoffman is still attached.