Hi there.



"It's too bad she won't live, but then again, who does ?" is the same as



"It's too bad (that) she will not live, but then again, who does (live)?"



"Who does?" is the "short answer" for "Who does live?"



"Short answers" are very common in English.



Short answer: Answers are often grammatically incomplete, because they do not need to repeat words that have just been said. A typical 'short answer' pattern is subject + auxiliary verb, together with whatever other wrods are really necessary.



Ex: "Does he swim?" "Yes, he does". ("swim" in not repeated)

Ex: "Has it stopped raining?" "No, it hasn't" ("stopped raining" is not repeated)

Ex: "Don't forget to call me!" "I won't" ("forget to call you" is not necessary)