It has spawned two feature films, with a third on the way, and has generated more than $13 billion in retail merchandise sales. adapting family entertainment to Broadway has brought mixed results, especially when not from Disney. Recent examples include “Matilda” (a hit), “Charlie and the Chocolate Factory” (a failure) and two outright bombs, “Seussical” and “Shrek the Musical” (though both have ended up with longer lives in high schools). If “SpongeBob” sinks on Broadway, it could damage a carefully cultivated two-decade-old brand.