Gratitude is always "bittersweet" to survivors.
I would venture to guess that those
17,000+ "hypothetical situation"
survivors would feel a mixture of relief, guilt, anguish and gratitude
in varying mixtures.
By the way! If 20,000+ had perished on Sept/11th at the WTC, that would have been a death-toll in the same league as the initial death-toll
from the A-bombing of Nagasaki [35,000 +]
Jacob