Genetic conditions which lead to deafness (as opposed to acquired ones) can already be diagnosed not only during pregnancy, but before the pregnancy exists via pre-implantation genetic diagnosis.
The science to select a deaf embryo or a hearing embryo, if you are a carrier for a genetic condition which causes deafness, is already here.
The science to diagnose acquired deafness will never be here.
It is not a past-tense ethical debate, but quite a present one.
"She thinks... she can make people do what she wants or needs, what is right, by the sheer force of her own talent, not by forcing them... she can teach them and persuade them... that they'll catch it from her. This is still faith in their rationality, in the omnipotence of reason. The mistake? Reason is not automatic. Those who deny it cannot be conquered by it. Do not count on them."