Stephen King says he may never write another novel. The master of the macabre has struggled with writing since he was struck by a van on June 19 while walking in his home state of Maine. King’s latest offering, “Hearts in Atlantis” remains on the New York Times bestseller list, but in a recent interview with NBC for “Today” and “Dateline,” King, 52, doubts his literary future: “There was this one awful minute when I sat there and I thought, ‘I can’t do this. I don’t know how to do this anymore.’ ” The author has had several operations and much rehabilitation since a van driven by Bryan Smith, 41, hit him. Smith was charged with aggravated assault and driving to endanger.