User blog comment:Corbierr/Random Trivia Blog :D/@comment-5180442-20140529221004/@comment-5180442-20140531223613

According to IMDb:

The film has its origins in a 1999 script entitled Grease  (1978) 3. Britney Spears  and Justin Timberlake  were to star as the children of Danny Zuko and Sandy Olsson from the 1978 film. The plot was virtually the same as that 'High School Musical', but with more similarities to 'Grease'. The character who would become Sharpay was to be the daughter of Betty Rizzo (producers tried to get Christina Aguilera  for the part, but she declined). Timberlake's band-mates from *NSYNC  were to have supporting roles. John Travolta  and Olivia Newton-John  allegedly were approached for cameo roles. But before the script went through a second re-write, the project was shelved until 2004.