In the end, Susan will have a different destiny instead of her brothers: she will be the one who will survive in the incident on the train.
"In The Last Battle, Susan is conspicuous por her absence. Peter says that she is "no longer a friend of Narnia", and (in Jill Pole's words) "she's interested in nothing now-a-days except nylons and lipstick and invitations." Similarly, Eustace Scrubb frases her as saying, "What wonderful memories you have! Fancy you still thinking about all those funny games we used to play when we were children," and Polly Plummer adds, "She wasted all her school time wanting to be the age she is now, and she'll waste all the rest of her life trying to stay that age. Her whole idea is to race on to the silliest time of one's life as quick as she can and then stop there as long as she can." Thus, Susan does not enter the real Narnia with the others at the end of the series. It is left ambiguous, however, whether or not Susan's absence is permanent, especially since Lewis stated elsewhere that:
The books don't tell us what happened to Susan. She is left alive in this world at the end, having por then turned into a rather silly, conceited young woman. But there's plenty of time for her to mend and perhaps she will get to Aslan's country in the end... in her own way.
In his Companion to Narnia, Paul F. Ford writes at the end of the entry for Susan Pevensie that "Susan's is one of the most important Unfinished Tales of The Chronicles of Narnia", but adds in Footnote 1 for that entry:
This is not to say, as some critics have maintained, that she is lost forever ... It is a mistake to think that Susan was killed in the railway accident at the end of The Last Battle and that she has forever fallen from grace. It is to be assumed, rather, that as a woman of twenty-one who has just lost her entire family in a terrible crash, she will have much to work through; in the process, she might change to become truly the gentle person she has the potential for being."
Well, Susan will change from a gentle girl to a presumptuous and vain lady: she will forget how she loved Narnia and probably she will paid for this with her survival: do you think it's right or wrong?