German Shepherd Q&A
I belive they will. All Black and all White GSD are born in the litters of the usual GSD colours, but are considered a fault. They make gorgeous pets and family members.
Actually according to the AKC only all white is considered a fault, and they can't be shown, all black is fine.
We have a five month old male that is all black, both his parents are all black and his grandparents were all black. They are a beautiful glossy black, very shiney coats, and are very loyal, guarding dogs.