What does Isaiah 23:15 mean?

At that time, Tyre will be forgotten for seventy years, the length of a king’s life. After seventy years, Tyre will be like the song about the prostitute: Isaiah 23:15 - Modern Text Bible

(Tyre will be out of the picture for a full generation. When it returns, it will be like an old song about a prostitute—famous, but not respected.)