While the “Karate Kid” remake being a smash hit is another “crane kick” to the privates for spec writers, there are signs that studios might be warming to original material again as audiences have largely given the cold shoulder to this summer’s crop of sequels, remakes and flimsy adaptations. Putting aside the power of Pixar—an outfit that has earned our loyalty like none other—and “Toy Story 3,” the summer’s tepid ticket sales have studios in a panicky mood about their product.