Clive Owen could easily play a slightly older version of Sufjan Stevens. I doubt they're much more than a decade apart (if that), but Clive's face already has a lot of time-wrought character whereas Sufjan still has cheeks as smooth as a prep schooler. Does Sufjan act? With all his other talents, I'm sure he can manage a few lines here or there. You know what he could have been great in?! If they had flashed back in Children of Men to when he and Julianne Moore's character were expecting!
Who would have played Julianne Moore? Let me think. Lindsay Lohan? I'm not sure she would age-match Sufjan. I'm also not sure there's enough insurance money in the world. But she has the red hair, freckles, and cat eyes. No, now that I look at a picture of her I see that her coloring is totally different. But Emma Stone might be a reasonable option.