Violet is supposing, in 'Normal', that things will be different, because they have been through something dramatic. Do you think most teenagers would change after something like this?

Most teenagers, at least those in the novel, will likely not be changed by this event. While Violet tends to be more sensitive, intellectual and thoughtful, the others will likely simply be happy they have their feed back. They think little outside of their own small worlds, and thus a tragedy where no one perished is minimal.