What new classics have we declared off-limits?
Why someone would want to remake it: The sleeper hit's plot is simple, easily relatable and could be adapted for virtually any time, place or culture. It's not difficult to imagine someone pitching an adaptation using two famous rappers, two rising metalheads or two flavor-of-the-month top 40 teen idols now or thirty years from now.
Why they shouldn't: Leads Glen Hansard and Marketa Irglova -- both veteran musicians with limited acting experience -- had an instantly recognizable onscreen chemistry (they were together in real life) which formed the foundation for the entire film. "Once" is a graceful, heartfelt exploration of friendship, love and the power of music that goes beyond its simple set-up. It's the sort of of perfect combination of material and performers that usually only happens, well, once.