Why the hell would you need a prequel of Freddy becoming Freddy when you have the entire series to tell you what happened before the original? The only way I would see a prequel to Nightmare is if they had the Elm Street kid's (Nancy, Rod, Glen, Tina, etc.)older siblings who died prior to the events of the original. I think this was mentioned in a deleted scene when Marge explains to Nancy about who Freddy was.
Anywho, I'm looking forward to the remake. It seems to have an amazing cast so far, and I'm dying to know who will be playing Nancy and Kris!