This point is made above, but, for me, this is the obstacle I'd worry about: The fact that the incest is not potential but has been committed seems like an issue. Would audiences today be able to stay focused on the story knowing that Jocasta and Oedipus already have children?
Perhaps this is not a major issue, but it seems like an issue none-the-less.
Excellent points so far. I'd add the whole concept of the incestuous relationship. I can see the trailer now: two people in bed, and the woman says to the man, "I love you like a son," or some other such drivel. A lot of the other elements would actually be quite appealing--the murder of Lauis would be good cinema; the battle of the wills with Oedipus, Tiresias, and Creon would make for good drama, as well. It's the marriage and the kids from that marriage which would steal the show in today's hypersexualized world. Just can't see it working as a movie for a modern audience.
Since the Chorus of the Greek play would not fit into a modern production, some other way of representing the thoughts and judgments pronounced would have to be found. Perhaps another character could be used, but there is some narration that would still have to be accounted for.
In the original play, a lot of the action takes place off stage. Laius is murdered, Jocasta hangs herself, and Oedipus rips out his eyes, all out of sight of the audience. Others come out and tell us about the gore and the blood and the death. But modern audiences are not patient with "off-stage" action, and would want to see the action. But in this case, the action is so gruesome, particular the part where Oedpius uses his wife's brooches to rip out his own eyes, that it would be really difficult to watch... at least for most people.