If there ever was a Deus ex movie it should be based on the first game not the one that tried to copy it. The plot was better, the characters were far more interesting (I don't think anyone could argue on that one) and while the "prequel" might be a good place to start from it doesn't match on the settings.
Dx3 was more futuristic than Dx1, yet is supposed to have happened before, so go figure.
John Travolta or Christian Bale for JC!
Not to mention that to have any chance at all they would need a decent budget, director, writer and a cinematographer to go with it anyways.