The possibilities are endless. Fresh off the success of The Sound of Music, NBC is planning to air a yet-unnamed live musical in the 2014 holiday season, the network announced Monday. “All weekend, people have been calling us and emailing us,” said NBC entertainment chairman Robert Greenblatt. “Rights holders of musicals have said ‘Please do one of our shows.’ We’re excited to try it again.” He also said they could do even more. The live Sound of Music production gave the network its best ratings since the 2009 series finale of ER.