I think there COULD be enough people to buy truck vended grilled cheese, BUT the name is so generic that nothing stops “The Grilled Cheese Van Man” the “Grilled Cheese Mobile” The “Grilled Cheese and Gourmet Hot Dog Truck”, etc. from shadowing it or at least putting a dent in the profits. Even an extraordinary grilled cheese cold be mimicked if need be.
Or better yet The Grilled Cheese with Bacon samich Truck