hmmmm.
here's my two cents.
if the chick was born without eyes, but is able to get around, eat drink etc. then he or she doesn't really know they are "different." i think it would be a different thing if this was a chicken who had sight and then lost it - that would be a much rougher sort of situation. as this chicken will grow up blind, i suspect it's quality of life will be okay, it will learn how to adapt and do things without sight provided you make any necessary adjustments in its living are. i think the idea of raising it with a couple of silkie chicks is a nice one. it would be ideal of the blind chick had friends that he or she could "flock" with. obviously this is one of those decisions that will have much to do with how much time and attention you will be able to put into raising this "special" animal and what your personal feelings about such things are. obviously you are a concerned and sensitive sort of person who takes things seriously and i'm sure whatever decision you make will be a sound one.
good luck!