They must prepare the family for the worst case scenario. To do otherwise would be irresponsible (and open themselves to malpractice lawsuits).
24 weeks is very, very early, but how developed their lungs are is a real key, and the technology exists to help the lungs develop outside the womb. There are younger premies who pull through. Body weight is another factor.
But remember a Great Truth - as long as the heart continues to beat, there is hope. Infants the size of the palm of a hand, weighing in at mere ounces, have survived to live long, happy lives.
I shall hope with you.
I am
Dawg