Be afraid.

Playbill lists the following plays and musicals as being in the works for future presentation on Broadway (to be fair, some sound like they might be pretty decent, but most sound pretty horrifyingly bad -- remember, these aren't just ideas, they're actually projects that have progressed far enough that they are considered to be "in the works"): 

Angels (musical based on Milton's Paradise Lost) 

Betty Boop (musical based on the 1930s cartoon) 

Big Time (musical about "down-on-their-luck lounge singers on a U.N. cruise ship that is held hostage by terrorists") 

Bring It On: The Musical (based on the movie about competitive cheerleading) 

Bruce Lee: Journey To the West (biographical musical about Bruce Lee, book being written by David Henry Hwang, music by David Yazbeck, both of whom I respect, but Bruce Lee?  Srsly?) 

Father Of the Bride (musical based on the Spencer Tracy film) 

Houdini (biographical musical by David Yazbeck, Danny Elfman and Kurt Anderson)

Liberace: The Man, the Music And the Memories (biographical musical) 

Merry-Go-Round ("New musical about a troubled young man whose estranged father helps him travels back in time on the magical title device," music and lyrics by Richard and Robert Sherman) 

Nerds://A Musical Software Satire (musical about Bill Gates and Steve Jobs) 

The Nutty Professor (musical based on the Disney movie, music by Marvin Hamlisch, book and lyrics by Rupert Holmes, directed by Jerry Lewis, which might actually mean that this one could work.) 

Once (stage adaptation of the Irish movie) 

"Untitled Mandela/Apartheid Musical"

"Untitled Woodstock Musical"