Typical answer for on here... Get Rid!!. The only reason why dogs fail is that YOU FAIL THEM, they don't fail themselves....
It's called being realistic. Notice I wrote "if it's not interested", not that it isn't killing, chasing, hunting etc etc.
If you've got a sight hound with NO prey drive or interest in it's prime function by the time it's 15 months old, what would you do? Unfortunately, not all dogs make the grade as I am sure you know.
If you got plenty of time, space and money, keep it as a pet.
Cheers, D.