:Gracious me, you are confused! The Line of Succession is absolute, so when the Queen dies, the throne descends to the next person on the list (most likely Charles, if he is alive, or William if the former is not). If all three of those were to perish without any changes (i.e. the princes having children), then the throne would go to Andrew. 

 Thusly, the line only changes with deaths, legitimate births, conversions to Catholicism and marriages to Catholics. Any further questions? I'll gladly answer more! D † B