Nastia Liukin is cashing in her gold medal. A Wheaties box, Cover Girl ads, her own line of Vanilla Star Jeans… and, get ready Serena and Blair, an appearance on “Gossip Girl.” Mark Levy, president of Vanilla Star, told WWD: “Nastia is a new example of a sports figure. The Olympics shelf life is usually a month, and I feel this girl could have a 20-year career.” I guess we should expect Nastia on “Dancing With The Stars” in 2028.