I'm fairly certain editing sperm or eggs is going to be even more challenging than an embryo---think of the effects of meiosis alone.

Contrast your prediction of elective eugenics for offspring with my own for autologous bone marrow transplants for sickle cell anemia: sickle cell is a single point mutation, there's a lot of tissue that we can sequence and work with, you don't need to transform anywhere near 100% of the tissue to get a good therapeutic effect, and we already do cure sickle cell anemia with bone marrow transplants given the right circumstances. All of that is in part why I think you are completely wrong with your prediction.