I suppose it depends on the breeder.
If the puppy is getting older and no one wants to meet the price, the breeder will either lower the price or keep the dog, working with it and waiting for the right owner. Less scrupulous breeders will dump the dog or I suppose kill the dog -- I have heard some horror stories.
Normally, if the color, temperament, or drive of the puppies do not match a specific home, they will find a pet home and usually sell the puppy on a limited registration.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC