Well, we'd get a re-recording of the song to fit the movie, but I doubt they'd change it Much. In the Fat Albert Movie, for example, they just arranged some of the song differently, and they changed one lyric... and not by much, either. Oddly, just removing a referrence to Bill Cosby. That's about it.
So I could see them doing a remake with the same song, just sung by the different performers to be consistant with the rest of the film (provided that certain people will be recast)