Of Assassins, their Creeds, and white dudes

So, as you've probably heard by now, there's going to be an Assassin's Creed movie, with Michael Fassbender both starring and co-producing. I've only ever played like half an hour of the first game, so I have no real investment in the film, but I have noticed quite a bit of consternation about Fassbender's role in the movie. Specifically, it's the fact that he'll be playing the lead and that's a problem because Altair, the protagonist of the first game was Middle Eastern. Michael Fassbender is Anglo-German. Considering Ubisoft was also behind the Prince of Persia movie - a movie starring Jake Gyllenhaal as a decidedly white Persian - people are obviously concerned about white washing in the movie's casting.

Now, the thing is, everyone's assuming that he's going to play Altair because they think the movie is going to be a straight-up adaptation of the first Assassin's Creed. However, I have some thoughts on that after the jump.

Every time Michael Fassbender smiles,
ovaries in a fifty mile radius are destroyed.

How do we know he's going to play Altair? He could play Desmond, Altair's descendent, whom the games all revolve around. If he does play an assassin, who's to say it will be Altair? Like I said, people are assuming that the movie will be a direct adaption of the first game, but I don't think many have considered the possibility that it might be based on the games, but with a wholly original plot. That makes more sense to me, because otherwise people will go into the theater basically knowing what's going to happen because they're either played Assassin's Creed or read the plot summary on Wikipedia or the Assassin's Creed Wiki.
The thing to keep in mind is that not all of Desmond's ancestors were Arab. Ezio was Italian and AC III's protagonist is half-British, half-Native American (which explains the tomahawk), so there's potentially room in there for Fassbender.

Pictures via the Assassin's Creed Wiki and Total Film.