Outside the three movies based on his TV characters, Cohen has not been front and center on the big screen. Could he even carry this movie? And should he be worried about being connected to the project in any way? The three actors previously linked to the redo are a who's who of comic talent gone sour, and there's no reason to think Cohen won't follow suit. If he signs on, we can expect another two or three years to go by until a new casting rumor or announcement replaces him with the latest funnyman-of-the-hour.
The thing is, it doesn't really matter who plays Mitty so much as whether there's a good story there. In addition to going through multiple actors, the film has been linked to a number of screenwriters, including Richard La Gravenese, who had prior experience with wild imaginations on The Fisher King. This kind of fantastical daydream premise has been done over and over in the 63 years since the first film, and it can be done as artsy as a Science of Sleep or Pan's Labyrinth or as broad as an Imagine That or Bedtime Stories.
You'd think Fox would be more interested in the latter direction, yet the current script is by Oscar-nominee Peter Morgan, known for grown-up fare like The Queen and Frost/Nixon. He also recently worked on the next James Bond installment, though it's uncertain whether his screenplay will be used. In Morgan's version of Walter Mitty, the character is reportedly a "timid mega-store owner" rather than a pulp magazine editor, as he is in the earlier film adaptation.
Directors linked to the project in the past include Steven Spielberg and Ron Howard, and Cohen could desire a similarly prestigious filmmaker now that he is working with Martin Scorsese on The Invention of Hugo Cabret. While it would be terribly unlikely, my predictable pick for director is Terry Gilliam, who recently presented Cohen, an admitted Monty Python fan, with the Peter Sellers Award for comedy at February's Evening Standard British Film Awards. For the time being, I'll just have to daydream what such a collaboration might look like.