We already have an aristocracy that can afford better schools, better neighborhoods, and the like. If designer babies one day leads to no more birth defects or unwanted children it is not a future to be feared.

there will always be people who have an advantage over others, the majority simply comes from where you were born followed to whom to you were born too.

The real fear is likely that some will make choices that are not politically correct, it is certain this would happen in non Western countries.