“A lot of things have happened this year for Disney Theatrical Productions: the closing of ‘Beauty and the Beast’ after 13 years; the steady weeks of million-dollar grosses for ‘Mary Poppins’ on Broadway and the demise of its struggling London counterpart; and the belated entry of ‘High School Musical’ into the Disney theatrical catalog. There was also, of course, that ‘Tarzan’ unpleasantness.” Next, “The Little Mermaid” will sneak onto Broadway, obscured so far by Mel Brooks’ latest publicity-sucking behemoth.