Her voice is so contemporary and R&B, I think she would need something written for her. And also her appeal is somewhat that she sings songs that she's written and plays the piano. From performing SO MUCH the last four years, her voice isn't what it was when she recorded "Fallin," so I'm not sure if her voice alone would give her a ticket to Broadway.
Maybe something in The Wiz revival? She's too old for Dorothy and too young for Glinda.
Eeeeeeyyyyyyyyaaaaaaaannnnnddddd aaaaaaaiiiiiiiiyyyyyyaaaaaammmmmmmm teeeeeeeelllllliiiiiinnngg yyyyooooooouuuuuuuwwwaaaahh...