He has really great during his run, I dont see why people think CC was grooming him for something, the show never changed its name and there is really not a lot of places to go for mocking American bipartisanship.
Keep in mind he is the executive producer of the Colbert Report. He's doing what he loves; works(tapes- work day is longer) 22min per day, four days per week, and three-weeks on one-week off. Plus holidays. He has time left in him. The movie is more about that particular story than Mr. Stewart's desire to be a filmmaker. I see him on for at least another ten years, maybe its just wishful thinking.
And yes, he should employ those guys in some capacity. At the minimum, he could throw some writing work to Andy and use him as a foreign correspondent.