Bump- well, this isn't a Johnny related update, but apparently this film is alive again, with Daniel Trachtenberg in talks to direct. A couple of years ago I would've really loved for Johnny to do this- it'd be a relatively realistic role after so many fantasy ones, but still have the interest of the magic and other facets of Houdini's life (I think he was interested in seances and the like). Now, though, it seems that his upcoming film schedule is so crowded that adding this one would be a bit much, I think- I don't want him to stretch himself too thin. Again, there is no mention of him being considered for this- the article only mentions that he was once in talks for this.
Here is a new article from Flickering Myth with Trachtenberg now set to direct. It mentions Johnny previously circling the role, but no mention of who will star now. (Probably not Johnny, his plate is too full now, I think).