No I don't think she will because if the writers were going to kill off one of the main characters they would want to suprise 你 make it happen from nowhere so 你 dont expect it.
She could die in the flash sideways.. that doesn't mean she is dead on the island. I don't know how they are going to connect the 2004 lives of the passengers with the 2007 (on the island) lives. Can't wait to find out!